Sen. John McCain predicted Sunday that the public would learn more about the relationship between President Donald Trump's 2016 presidential campaign and the Russian government.
In an interview on CNN's "State of the Union," the Arizona Republican said there were "a lot of things about our relations with Russia that trouble me a lot."
He cited the removal of a provision in the 2016 Republican party platform that supported sending lethal weapons to Ukraine, a move that was "not the will of most Republicans."
"There's a lot of aspects of this whole relationship with Russia and Vladimir Putin that requires further scrutiny. And so far, I don't think the American people have gotten all the answers," McCain said. "I think there's a lot more shoes to drop from this centipede."
John McCain through the years
John McCain through the years
UNITED STATES - FEBRUARY 27: TV RATINGS--Senate Commerce Committee Chairman John McCain, R-Ariz., during hearing on the TV ratings system. (Photo by Douglas Graham/Congressional Quarterly/Getty Images)
20th August 1992: The Republican Senator from Arizona, John McCain, speaking at the Republican National Convention. A fomer prisoner of war for several years in Vietnam, he contested his party's nomination for the 2000 election. (Photo by Consolidated News Pictures/Getty Images)
HANOI, VIET NAM: U.S. Sen. John McCain, a former POW, looks 31 May 1993 at a display of personal belongings of American POWs at the joint POW/MIA archives center in the Hanoi Army Museum. McCain is with U.S. Sen. John Kerry and a delegation on a two-day visit aimed at obtaining more access to archives dealing with the fate of missing U.S. servicemen. (Photo credit should read HOANG DINH NAM/AFP/Getty Images)
UNITED STATES - MAY 18: MCCAIN'S DAY--Sen John McCain, R-Ariz., relaxes in his office at about 2:15 p.m. (Photo by Scott J. Ferrell/Congressional Quarterly/Getty Images)
UNITED STATES - JUNE 02: McCAIN BILL--John McCain,R-Ariz.,during a press conference on the McCain Bill and tobacco legislation. (Photo by Douglas Graham/Congressional Quarterly/Getty Images)
WASHINGTON, : US Senator John McCain, R-AZ, chairman of the Senate Committee on Commerce, Science and Transportation begins the start of a hearing on the investigation of the scandal surrounding the 2002 Salt Lake City Winter Olympics on Capitol Hill in Washington, DC 14 April, 1999. AFP PHOTO/Mario TAMA (Photo credit should read MARIO TAMA/AFP/Getty Images)
HANOVER, : US Senator John McCain speaks to reporters 27 October,1999 in Hanover, New Hampshire. McCain criticized sugar, oil, and corn (shown behind) subsidies and linked them to 'soft money' campaign contributions. (ELECTRONIC IMAGE) AFP PHOTO Luke FRAZZA (Photo credit should read LUKE FRAZZA/AFP/Getty Images)
MANCHESTER, : Republican president hopeful John McCain greets supporters as he arrives at a debate forum sponsored by a local television station 02 December, 1999, in Manchester, New Hampshire. McCain will debate the other Republican candidates seeking the party's presidential nomination. (DIGITAL IMAGE) AFP PHOTO/John MOTTERN (Photo credit should read JOHN MOTTERN/AFP/Getty Images)
UNITED STATES - CIRCA 2000: John McCain addresses a shadow convention at the Annenberg Center of the University of Pennsylvania. McCain was booed when he asked suppoters to back his former primary opponent, George W. Bush. The shadow convention was put on near the site of the Republican National Convention in Philadelphia to highlight issues that the organizers say the major parties are ignoring. (Photo by Harry Hamburg/NY Daily News Archive via Getty Images)
CAMDEN, UNITED STATES: GOP presidential hopeful US Senator John McCain (R-AZ) waves during an 'Old Fashion BBQ and Stump Meeting' on the front yard of a supporter's house 08 January 2000 in Camden, South Carolina. (ELECTRONIC IMAGE) AFP PHOTO/Paul J. RICHARDS (Photo credit should read PAUL J. RICHARDS/AFP/Getty Images)
PETERBOROUGH, NH - JANUARY 30: Republican presidential hopeful Sen. John McCain (L) and his wife Cindy are showered with confetti following McCain's final town meeting 30 January, 2000 in Peterborough, New Hampshire. (ELECTRONIC IMAGE) (Photo credit should read C.J. GUNTHER/AFP/Getty Images)
GREENWOOD, : Republican presidential hopeful John McCain makes a point 14 February 2000 during a town hall meeting at the American Legion Post 20 in Greenwood, South Carolina. McCain is campaigning heavily in the southern state against Texas Governor Geroge W. Bush ahead of the 19 February 2000 primary. (ELECTRONIC IMAGE) AFP PHOTO/Tim SLOAN (Photo credit should read TIM SLOAN/AFP/Getty Images)
THE TONIGHT SHOW WITH JAY LENO -- Episode 1789 -- Pictured: (l-r) Senator John McCain during an interview with host Jay Leno on March 1, 2000 -- (Photo by: Paul Drinkwater/NBC/NBCU Photo Bank via Getty Images)
UNITED STATES - APRIL 30: Sen. John McCain, R-AZ, at a Senate Commerce, Science and Transportation Committee hearing on climate change. (Photo By Tom Williams/Roll Call/Getty Images)
UNITED STATES - FEBRUARY 12: TEMPORARY GUEST WORKERS--Witness Sen. John McCain, R-Ariz., during the Senate Judiciary Immigration, Border Security and Citizenship Subcommittee hearing titled 'Evaluating a Temporary Guest Worker Proposal.' (Photo by Scott J. Ferrell/Congressional Quarterly/Getty Images)
UNITED STATES - JUNE 28: SENATE POLICY LUNCHES--Sen. John McCain, R-Ariz., talks to reporters after the Senate GOP policy luncheon. (Photo by Scott J. Ferrell/Congressional Quarterly/Getty Images)
WASHINGTON - SEPTEMBER 20: U.S. Senator John McCain (R-AZ) addresses The Northern Virginia Technology Council's Titans breakfast at the Capitol Hilton September 20, 2006 in Washington, DC. McCain spoke on a variety of subjects, including telecommunications legislation, net neutrality, research and development tax credits, immigration, and Internet taxes. He also addressed the rift that he and several other Republican senators are having with the White House over the Geneva Conventions. (Photo by Chip Somodevilla/Getty Images)
KABUL, AFGHANISTAN - JULY 04: US Senator John McCain (C) holds a press conference at ISAF HQ in Kabul, Afghanistan on July 4, 2017. US Senator John McCain visited the headquarters of NATO-led mission after his visit at Pakistan. (Photo by Haroon Sabawoon/Anadolu Agency/Getty Images)
WASHINGTON, July 13, 2017 -- U.S. Senator John McCain is swarmed by reporters as he leaves a meeting on Capitol Hill in Washington D.C. July 13, 2017. Senate Republicans of the U.S. Congress on Thursday unveiled a new healthcare bill that they hoped can fulfill their long-time goal to 'repeal and replace' the Affordable Care Act. (Xinhua/Ting Shen via Getty Images)
"I think he and others need to be questioned," McCain said, adding that Stone also had ties with ousted former Ukrainian President Victor Yanukovych, a Kremlin ally.
"This whole issue of the relationship with the Russians and who communicated with them and under what circumstances clearly cries out for investigation," he said. "But I would also point out we should not assume guilt until we have a thorough investigation. I'm not judging anyone guilty."
The Arizona senator also dismissed Trump's unfounded claim last weekend that former President Barack Obama personally ordered the wiretapping of Trump Tower phones because of his suspected ties to Russia.
"President Trump has to provide the American people, not just the Intelligence Committee, but the American people, with evidence that his predecessor, former president of the United States, was guilty of breaking the law, because our director of national intelligence, General Clapper, testified that there was absolutely no truth to that allegation," McCain said.
He continued: "So, I think the president has one of two choices: either retract or to provide the information that the American people deserve. Because, if his predecessor violated the law, [if] President Obama violated the law, we have got a serious issue here, to say the least."
The senator has remained engaged in the current inquiry into Russia's involvement in the election.
McCain is one of several Republicans who have called for an independent congressional investigation of Russia's interference in the 2016 election, and has warned of Russia's attempts to use similar tactics in the German and French elections this year.
But while he has emerged as an outspoken critic of the new administration's foreign policy worldview, some skeptics argue McCain has rarely gone further than voice his displeasure with Trump. Despite his longtime depiction as a "maverick," McCain has only voted against Trump's position a handful of times, though his chances to do so thus far have been limited.