Mitt Romney called in to "Your World with Neil Cavuto" on Fox News Wednesday demanding to see tax returns for the top three GOP candidates, saying specifically that he expects a "bombshell" from frontrunner Donald Trump's most recent filings.
The 2012 Republican nominee for president briefly gave his thoughts on what additional policy positions he'd like to see from candidates Trump, Marco Rubio and Ted Cruz before hitting the three hard on tax disclosures he says are still outstanding.
"I'd like to see where they filed their taxes in the last several years. I'm not talking about their taxes this year, I'm talking about the taxes that have already been filed with with the IRS, and Donald Trump and Marco Rubio and Ted Cruz have not shown us their back taxes."
Noting that this was an issue during his own run in the last presidential election, Romney said, "I think we have good reason to believe that there's a bombshell in Donald Trump's taxes."
See more of Donald Trump through the years:
Donald Trump through the years
Mitt Romney on Donald Trump: 'There's a bombshell' in his taxes
Real estate developer Donald Trump annouces intentions to build a $100 million dollar Regency Hotel. (Photo by John Pedin/NY Daily News via Getty Images)
UNITED STATES - MARCH 02: Donald Trump with Alfred Eisenpreis, New York City Economic Development Administrator. Sketch of new 1,400 room Renovation project of Commodore Hotel. (Photo by NY Daily News Archive via Getty Images)
NEW YORK, NY - 1980: Donald Trump and Ivana Trump attend Roy Cohn's birthday party in February 1980 in New York City. (Photo by Sonia Moskowitz/Getty Images)
UNITED STATES - MAY 26: Donald Trump stands behind architect's model of City Hall Plaza. (Photo by Frank Russo/NY Daily News Archive via Getty Images)
Donna Mills and Donald Trump during 1983 Annual American Image Awards at Sheraton Center in New York City, New York, United States. (Photo by Ron Galella, Ltd./WireImage)
Portrait of real estate mogul Donald John Trump (b.1946), smiling slightly and facing to his right, 1983. New York. (Photo by Bachrach/Getty Images)
New York real estate magnates Steve Ross, right, and Donald Trump, left, announce agreement, Thursday, August 1, 1985 in New York, to merge the Houston Gamblers and the New Jersey Generals United States Football League teams. Ross heads a group of investors that last week agreed to buy the troubled Houston franchise. (AP Photo/Marty Lederhandler)
Real estate magnate Donald Trump poses in front of one of three Sikorsky helicopters at New York Port Authority's West 30 Street Heliport on March 22, 1988. (AP Photo/Wilbur Funches)
Ivana Trump and Donald Trump during Mike Tyson vs Michael Spinks Fight at Trump Plaza - June 27, 1988 at Trump Plaza in Atlantic City, New Jersey, United States. (Photo by Ron Galella/WireImage)
Donald Trump and his wife, Ivana, pose outside the Federal Courthouse after she was sworn in as a United States citizen, May 1988. (AP Photo)
NEW YORK, NY - DECEMBER 4: Billionaire Donald Trump and his wife Ivana arrive 04 December 1989 at a social engagement in New York. (Photo credit should read SWERZEY/AFP/Getty Images)
Shown in photo is Donald Trump, Nov. 20, 1990. (AP Photo/Mark Lennihan)
Billionaire developer Donald Trump, right, waits with his brother Robert for the start of a Casino Control Commission meeting in Atlantic City, N.J., March 29, 1990. Trump was seeking final approval for the Taj Mahal Casino Resort, one of the world's largest casino complexes. (AP Photo)
Developer Donald Trump, center, is flanked by super middleweight champion Thomas Hearns, left, of Detroit, and Michael Olajide of Canada at a news conference in New York Thursday, Feb. 15, 1990. The three announced the super middleweight title bout at Trump Taj Mahal Casino Resort at Atlantic city, N. J on April 28.(AP Photo/Timothy Clary)
Real estate magnate Donald Trump and his girlfriend Marla Maples are seen at the Holyfield-Foreman fight at Trump Plaza in Atlantic City, N.J., April 19, 1991. (AP Photo)
Donald Trump and Daughter Ivanka Trump during Maybelline Presents 1991 Look of the Year at Plaza Hotel in New York City, New York, United States. (Photo by Ron Galella/WireImage)
NEW YORK, NY - APRIL 7: Donald Trump touches 07 April 1993 Marla Maples stomach to confirm published reports that the actress is pregnant with his child. The two arrived for Maples appearance in the Broadway musical 'The Will Rogers Follies'. (Photo credit should read HAI DO/AFP/Getty Images)
NEW YORK, NY - DECEMBER 21: US business tycoon Donald Trump(C) enters the PLaza Hotel in New York past supporters 21 December 1994. Hundreds of supporters showed up at a news conference where Trump denied a New York newspaper report that the Sultan of Brunei had bid 300 million USD to buy the Manhattan hotel. (Photo credit should read DON EMMERT/AFP/Getty Images)
FILE--This is a 1994 file photo of Donald Trump. Trump said Wednesday, Oct. 23, 1996 he has bought the Miss Universe, Miss USA and Miss Teen beauty pageants from ITT. ``It's a done deal,'' Trump said in a telephone interview. ``It's a very, very great entertainment format. It gets very high ratings, it's doing very well and we'll make it even better.'' Trump declined to say how much he paid. Asked if a New York Post source was correct in saying the deal was worth tens of millions of dollars, Trump replied, ``Why not? (AP Photo/Jim Cooper)
FLUSHING MEADOWS, UNITED STATES: Donald Trump and his girlfriend Celina Midelfar watch Conchita Martinez and Amanda Coetzer 07 September at US Open in Flushing Meadows, NY. AFP PHOTO Timothy CLARY (Photo credit should read TIMOTHY CLARY/AFP/Getty Images)
Donald Trump and Christine Whitman during Opening of New Warner Bros. Store in Trump Plaza Casino at Trump Plaza Casino in Atlantic City, New Jersey, United States. (Photo by Ron Galella/WireImage)
In this June 7, 1995 file photograph, Donald Trump is seen above the floor of the New York Stock Exchange after taking his flagship Trump Plaza Casino public in New York City. Trump Entertainment Resorts Inc., based in Atlantic City, New Jersey, filed for Chapter 11 protection on Tuesday, Feb. 17, 2009, in the U.S. Bankruptcy Court in New Jersey. Trump and his daughter Ivanka resigned from the company's board Friday, Feb. 13, 2009, after growing frustrated with bondholders. (AP Photo/Kathy Willens,File)
Celine Dion, husband Rene, Donald Trump & Ivanka Trump (Photo by KMazur/WireImage)
Entrepreneur Donald Trump watches an undercard fight as an unidentified companion whispers into his ear before the start of the Mike Tyson versus Francois Botha bout at the MGM Grand Hotel & Casino in Las Vegas, Nevada, Saturday, Jan. 16, 1999. (AP Photo/Eric Draper)
Developer Donald Trump holds an umbrella as he walks Saturday, Nov. 9, 2002, to the 11th green of the Ocean Trail Golf Club in Rancho Palos Verdes, Calif. Trump plans to turn the beleagured golf club into a world class course. Trump intends to close on the golf club by December and hopes to begin improvements by January. He could reopen the course, 20 miles south of Los Angeles, as early as June. (AP Photo/Damian Dovarganes)
Entrepreneur Donald Trump (L) and Rev. Al Sharpton speak at a ribbon cutting ceremony for Sharpton's National Action Network Convention April 5, 2002 in New York City. The group aims to further the development of civil rights. (Photo by Mario Tama/Getty Images)
Donald Trump and his girlfriend Melania Knauss attend the Marc Bouwer/Peta Fall/Winter 2002 Collection show February 14, 2002 during Mercedes-Benz Fashion Week in New York City. (Photo by George De Sota/Getty Images)
NEW YORK, UNITED STATES - DECEMBER 06: WBC Kampf im Schwergewicht 2003, New York/Madison Square Garden; Vitali KLITSCHKO/UKR - Kirk JOHNSON/CAN; Donald TRUMP als Zuschauer (Photo by Alexander Hassenstein/Bongarts/Getty Images)
FOXBORO, MA - JANUARY 10: Donald Trump stands on the sidelines before the start of the AFC divisional playoffs between the New England Patriots and Tennessee Titans on January 10, 2004 at Gillette Stadium in Foxboro, Massachusetts. Temperatures have reached as low as 7 degrees in the Foxboro area. (Photo by Al Bello/Getty Images)
US tycoon Donald Trump arrives to speak at the annual Conservative Political Action Conference (CPAC) at National Harbor, Maryland, outside Washington, on February 27, 2015. AFP PHOTO/NICHOLAS KAMM (Photo credit should read NICHOLAS KAMM/AFP/Getty Images)
NASHVILLE, TN - APRIL 10: Donald Trump speaks during the NRA-ILA Leadership Forum at the 2015 NRA Annual Meeting & Exhibits on April 10, 2015 in Nashville, Tennessee. The annual NRA meeting and exhibit runs through Sunday. (Photo by Justin Sullivan/Getty Images)
WASHINGTON, DC - MARCH 24: Real estate mogul and billionaire Donald Trump attends Golf legend Jack Nicklaus' Congressional Gold Medal ceremony in the U.S. Capitol Rotunda March 24, 2015 in Washington, DC. Trump announed on March 18 that he has launched a presidential exploratory committee. (Photo by Chip Somodevilla/Getty Images)
DES MOINES, IA - MAY 16: Businessman Donald Trump speaks to guests gathered for the Republican Party of Iowa's Lincoln Dinner at the Iowa Events Center on May 16, 2015 in Des Moines, Iowa. The event sponsored by the Republican Party of Iowa gave several Republican presidential hopefuls an opportunity to strengthen their support among Iowa Republicans ahead of the 2016 Iowa caucus. (Photo by Scott Olson/Getty Images)
Developer Donald Trump displays a copy of his net worth during his announcement that he will seek the Republican nomination for president, Tuesday, June 16, 2015, in the lobby of Trump Tower in New York. (AP Photo/Richard Drew)
Republican presidential hopeful Donald Trump gives a thumbs up before boarding his campaign plane to depart from Laredo, Texas, Thursday, July 23, 2015. (AP Photo/LM Otero)
AYR, SCOTLAND - JULY 30: Republican Presidential Candidate Donald Trump visits his Scottish golf course Turnberry with his children Ivanka Trump and Eric Trump on July 30, 2015 in Ayr, Scotland. Donald Trump answered questions from the media at a press conference. (Photo by Jeff J Mitchell/Getty Images)
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When pressed by Cavuto to clarify, Romney said, "Either he's not anywhere near as wealthy as he says he is, or he hasn't been paying the kind of taxes we would expect him to pay, or perhaps he hasn't been giving money to the vets or to the disabled like he's been telling us he's been doing.
"The reason that I think there's a bombshell in there," the former Utah governor continued, "is because every time he's asked about his taxes, he dodges and delays and says, 'Well, we're working on it.' Hey, we're not talking about the taxes that are coming due this year -- of course they're working on those; they won't be ready for months -- we're talking about taxes already filed. Back taxes."
Romney's tax returns were a significant issue during his campaign, something he at the time said should not be a campaign issue.
"They were all over me for my taxes -- became a big issue, but I put my taxes out in January of 2012 and that gave people a chance to digest it and decide whether I was going to be the nominee or not. And if in fact Donald Trump's taxes or Marco Rubio's or Ted Cruz's have some real problems in there, let's get them out and see them."
See Romney's campaigns for president:
Mitt Romney's campaigns for president
Mitt Romney on Donald Trump: 'There's a bombshell' in his taxes
**FILE** Massachusetts Gov. Mitt Romney speaks at a rally on the steps of the Statehouse in Boston, in this Sunday, Nov. 19, 2006 file photo, Romney's political record is relatively brief - four years as Massachusetts governor and two statewide campaigns - but that's enough for Brian Camenker to write a 28-page report that portrays Romney as sympathetic to gay rights and sexual behavior that clashes with his burnished image as a defender of traditional values. (AP Photo/Chitose Suzuki, File)
Former Massachusetts Gov. Mitt Romney shakes hands with first graders from Mead Hall Episcopal School during a campaign swing through South Carolina as he stops to be the Keynote speaker at a Rotary club meeting Monday, Jan. 29, 2007, in Aiken, S.C. (AP Photo/Mary Ann Chastain)
Republican Mitt Romney meets with the media after addressing the Detroit Economic Club in Detroit, Wednesday, Feb. 7, 2007. Romney used the first major policy speech of his fledgling presidential campaign to promote permanent tax cuts, portable health insurance and free and open markets. (AP Photo/Carlos Osorio)
Republican presidential candidate and former Massachusetts governor Mitt Romney signs a poster for Alex Stroman, of Chester, S.C. Wednesday, Feb. 14, 2007, at Seawell's in Columbia, S.C. Romney visited South Carolina as part of his official campaign kickoff tour following his announcement Tuesday that he's seeking the Republican presidential nomination. (AP Photo/Perry Baker)
Republican presidential candidate and former Massachusetts governor Mitt Romney holds one his granddaughter, Mia, 2, after speaking in Columbia, S.C. Wednesday, Feb. 14, 2007, as part of his official campaign kickoff tour. Romney visited South Carolina following his announcement Tuesday that he's seeking the Republican presidential nomination. (AP Photo/Perry Baker)
Republican presidential hopeful Mitt Romney talks to the nation's first presidential primary voters during a campaign stop at the Opera House in Derry, N.H., Tuesday, April 3, 2007.(AP Photo/Jim Cole)
Republican presidential hopeful, former Massachusetts Gov. Mitt Romney speaks to a potential voter on a cellphone at his campaign headquarters in Boston Wednesday, May 16, 2007, one day after the latest GOP presidential debate, and amid a daylong effort by his campaign to enlist 24,000 new supporters. (AP Photo/Elise Amendola)
Republican presidential hopeful Mitt Romney shakes hands during a campaign stop at Moulton's Market in Amherst, N.H., Wednesday, Aug. 1, 2007.(AP Photo/Jim Cole)
Presidential hopeful and former Massachusetts Gov. Mitt Romney, left, kisses 6-month-old Bennett Covington as he poses for a picture with the baby and his mother, Liz Covington, Thursday, September 27, 2007 , during a campaign stop at an IHOP in Sacramento, Calif. (AP Rich Pedroncelli)
Republican presidential hopeful former Massachussets Gov. Mitt Romney speaks to local residents during a campaign stop Saturday, Dec. 15, 2007, in Humboldt, Iowa. (AP Photo/Charlie Neibergall)
Republican presidential hopeful, former Massachusetts Gov. Mitt Romney, shakes hands with supporters at a campaign stop in Las Vegas, Nev., Thursday, Jan. 17, 2008. (AP Photo/LM Otero)
Republican presidential hopeful, former Massachusetts Gov. Mitt Romney, waves to supports during a primary day campaign rally in Tampa, Fla., Tuesday, Jan. 29, 2008. (AP Photo/LM Otero)
Republican presidential candidate, former Massachusetts Gov. Mitt Romney shakes hands during a campaign rally, Friday, Sept. 7, 2012, in Orange City, Iowa. (AP Photo/Evan Vucci)
A woman working in the room where Republican presidential candidate and former Massachusetts Gov. Mitt Romney will speak election night is silhouetted against a lighted campaign sign near the stage at the Boston Convention Center in Boston, Monday, Nov. 5, 2012. (AP Photo/Stephan Savoia)
Republican presidential candidate, former Massachusetts Gov. Mitt Romney speaks at a Florida campaign rally at Orlando Sanford International Airport, in Sanford, Fla., Monday, Nov. 5, 2012. (AP Photo/Charles Dharapak)
Republican presidential candidate and former Massachusetts Gov. Mitt Romney with his wife Ann greet supporters during a campaign rally at the International Exhibition Center in Cleveland, Sunday Nov. 4, 2012. (AP Photo/Jerome Delay)
Republican presidential candidate, former Massachusetts Gov. Mitt Romney speaks during a campaign event at the Newport News International Airport, Sunday, Nov. 4, 2012, in Newport News, Va. (AP Photo/David Goldman)
Republican presidential candidate and former Massachusetts Gov. Mitt Romney reaches out to shake hands with supporters as he campaigns at Colorado Springs Municipal Airport in Colorado Springs, Col., Saturday, Nov. 3, 2012. (AP Photo/Charles Dharapak)
Republican presidential candidate and former Massachusetts Gov. Mitt Romney carries Levi Vandenberg, five months, of Dover, N.H., after he picked him up from his mother and continued to walk down a ropeline of supporterrs as he campaigns at Portsmouth International Airport, in Newington, N.H., Saturday, Nov. 3, 2012. He later returned the baby to his mother. Ann Romney is seen at left. (AP Photo/Charles Dharapak)
Republican presidential candidate, former Massachusetts Gov. Mitt Romney talks with former Florida Gov. Jeb Bush as they fly on his campaign plane to Miami Fla., Wednesday, Oct. 31, 2012. (AP Photo/Charles Dharapak)
Republican presidential candidate and former Massachusetts Gov. Mitt Romney greets supporters as he campaigns at the Pensacola Civic Center in Pensacola, Fla., Saturday, Oct. 27, 2012. (AP Photo/Charles Dharapak)
Republican presidential candidate, former Massachusetts Gov. Mitt Romney, left, and vice presidential running mate Rep. Paul Ryan, R-Wis., wave to the crowd as fireworks go off during a campaign rally on Friday, Oct. 19, 2012 in Daytona Beach, Fla. (AP Photo/ Evan Vucci)
President Barack Obama, right, and Republican presidential nominee Mitt Romney shake hands following their third presidential debate at Lynn University, Monday, Oct. 22, 2012, in Boca Raton, Fla. (AP Photo/David Goldman)
Republican presidential candidate, former Massachusetts Gov. Mitt Romney shakes hands during a campaign event at Watson Truck and Supply, Thursday, Aug. 23, 2012, in Hobbs, N.M. (AP Photo/Evan Vucci)
Republican presidential candidate, former Massachusetts Gov. Mitt Romney pauses during a campaign event at Horizontal Wireline Services on Tuesday, July 17, 2012 in Irwin, Pa. (AP Photo/Evan Vucci)
Republican presidential candidate, former Massachusetts Gov. Mitt Romney smiles as he addresses supporters at his Super Tuesday campaign rally in Boston, Tuesday, March 6, 2012. (AP Photo/Stephan Savoia)
Republican presidential candidate, former Massachusetts Gov. Mitt Romney holds One-year-old Madison Busch during a campaign rally in Loveland, Colo., Tuesday, Feb. 7, 2012. (AP Photo/Gerald Herbert)
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After refusing for months to release information about his personal tax filings during the 2012 campaign, Romney eventually disclosed his 2011 return and a summary of his tax rates dating back to 1990 about six weeks before the election.
"Look, people have a right to know if there's a problem in those taxes before they decide who our nominee's going to be," Romney said. "The fact that [Trump] is so aggressive in avoiding any discussion of his taxes and is not willing to put them out so far suggests there's something in there he doesn't want us to see."