Senate Majority Leader Mitch McConnell warned House Democrats on Wednesday that any investigations of President Donald Trump under their new majority the next two years "might not be a smart strategy."
"The whole issue of presidential harassment is interesting," he told reporters Wednesday, in response to a question about what Senate Republicans would do if Democrats try to obtain the president's tax returns. "I remember when we tried it in the late '90s. We impeached President Clinton. His numbers went up and ours went down, and we underperformed in the next election."
"So the Democrats in the House will have to decide just how much presidential harassment they think is a good strategy," McConnell added. "I'm not so sure it'll work for them."
Democrats will make their own governing decisions regardless of his recommendation, said McConnell, who added that he was just making a "historical observation" that the GOP's investigations of Clinton "improved the president's approval rating and tanked ours."
Candidates casting their votes during the 2018 midterm election
Candidates casting their votes during the 2018 midterm election
Democratic candidate Christine Hallquist votes during the midterm election in Hyde Park, Vermont, U.S. November 6, 2018. REUTERS/Caleb Kenna
Democratic Congressional candidate Alexandria Ocasio-Cortez arrives to vote in the midterm elections in the Bronx, New York City, U.S., November 6, 2018. REUTERS/Andrew Kelly
Missouri Attorney General and Republican U.S. Senate candidate Josh Hawley, left, checks in to the polling place before voting, Tuesday, Nov. 6, 2018, in Columbia, Mo. (AP Photo/L.G. Patterson)
U.S. Rep. Beto O'Rourke (D-TX), candidate for U.S. Senate arrives with his family to vote in the 2018 midterm elections in El Paso, Texas, U.S., November 6, 2018. REUTERS/Mike Segar TPX IMAGES OF THE DAY
Republican candidate for Governor Ron DeSantis arrives to vote, carrying his daughter Madison, in the midterm elections at a polling place in Ponte Vedra Beach, Florida, U.S., November 6, 2018. REUTERS/Carlo Allegri
Democratic congressional candidate Ilhan Omar walks to the vote counting machine after filling out her ballot during midterm elections in Minneapolis, Minnesota, U.S. November 6, 2018. REUTERS/Eric Miller
Democratic gubernatorial candidate Andrew Gillum, center, carrying son Davis, age 16 months, leaves the polling place after voting with wife R. Jai, right, during midterm elections in Tallahassee, Florida, U.S. November 6, 2018. REUTERS/Colin Hackley TPX IMAGES OF THE DAY
Alaska independent U.S. House candidate Alyse Galvin smiles after emerging from a voting booth on Tuesday, Nov. 6, 2018, in Anchorage, Alaska. Galvin, who arrived at the polling location with her family, is challenging Republican U.S. Rep. Don Young for Alaska's lone U.S. House seat. (AP Photo/Becky Bohrer)
California gubernatorial Democratic candidate Gavin Newsom walks with his daughter, Montana, 9, to turn his ballot after voting Tuesday, Nov. 6, 2018, in Larkspur, Calif. (AP Photo/Eric Risberg)
Georgia Republican gubernatorial candidate Brian Kemp gives the thumbs up sign as he and youngest daughter Amy Porter leave after voting Tuesday, Nov. 6, 2018, in Winterville, Ga. Kemp is in a close race with Democrat Stacey Abrams. (AP Photo/John Bazemore)
Virginia Republican senatorial candidate Corey Stewart, center, and his wife Maria Stewart, left, voting at St. Margaret's Episcopal Church in Woodbridge, Va., Tuesday, Nov. 6, 2018. (AP Photo/Pablo Martinez Monsivais) Wife Maria Stewart
Marty Nothstein, Republican candidate in Pennsylvania's 7th Congressional District, arrive at his polling station to vote Tuesday Nov. 6, 2018, in New Tripoli, Pa. Nothstein is facing Democrat Susan Wild for the seat held by Charlie Dent who retired. (AP Photo/Jacqueline Larma)
Anthony Brindisi, left, Democratic candidate for New York's 22nd Congressional District, casts his vote at Mohawk Valley Community College in Utica, N.Y., Tuesday, Nov. 6, 2018. Brindisi, a Democratic Assemblyman, is hoping to defeat Republican Congresswoman Claudia Tenney in New York's 22nd Congressional District race. Pictured at right are his wife, Erica McGovern Brindisi, and his daughter, Lily Grace Brindisi. (AP Photo/Heather Ainsworth)
Democratic congressional candidate Amy McGrath checks in with poll workers before voting on Election Day in Georgetown, Ky., Tuesday, Nov. 6, 2018. (AP Photo/Bryan Woolston)
Haley Stevens, candidate for Michigan's 11th Congressional District, gives a thumbs up as exits her polling place Tuesday, Nov. 6, 2018, in Rochester Hills, Mich. Stevens is running against Lena Epstein. (AP Photo/Carlos Osorio)
Candidate for Pennsylvania's 1st Congressional District Rep. Brian Fitzpatrick, R-Pa., gestures after casting his ballot in Langhorne, Pa., Tuesday, Nov. 6, 2018. (AP Photo/Matt Rourke)
California gubernatorial Democratic candidate Gavin Newsom ties the shoe laces of his son Hunter, 7, as his son, Dutch, 2, looks on after voting Tuesday, Nov. 6, 2018, in Larkspur, Calif. (AP Photo/Eric Risberg)
Dana Balter, candidate for the House of Representatives in New York's 24th Congressional District, applies her "I Voted" sticker after casting her vote in Syracuse, N.Y., Tuesday, Nov. 6, 2018. (AP Photo/Adrian Kraus)
AGUA DULCE, CA - NOVEMBER 06: Democratic Congressional candidate Katie Hill (L) shakes hands with a poll worker after casting her ballot at a polling place in California's 25th Congressional district on November 6, 2018 in Agua Dulce, California. Republican incumbent U.S. Rep. Steve Knight is competing against Hill for his seat in the district in a close race. Political races across the country are being hotly contested for House and Senate seats. (Photo by Mario Tama/Getty Images)
COSTA MESA, CA - NOVEMBER 06: Longtime Rep. Dana Rohrabacher (R-Costa Mesa) passes people heading toward a polling place as he walks with family members after dropping off his ballot on November 6, 2018 in Costa Mesa, California. According to recent polling, Rohrabacher and Democratic challenger Harley Rouda are in a virtual tie to represent the 48th Congressional district. (Photo by David McNew/Getty Images)
COLUMBIA, MO - NOVEMBER 06: Missouri's Republican U.S. Senate Candidate Josh Hawley casts his vote on election day at The Crossings Church on November 6, 2018 in Columbia, Missouri. Hawley, the current Missouri Attorney General, is hoping to unseat current Democratic incumbent Senator Claire McCaskill. (Photo by Michael Thomas/Getty Images)
TURLOCK, CA - NOVEMBER 06: Republican U.S. Rep. Jeff Denham of California's 10th Congressional District casts his vote at the Berkeley Ave Baptist Church on November 6, 2018 in Turlock, California. Denham, a four-term Republican incumbent and Air Force veteran, is competing against Democratic challenger Josh Harder in one of seven closely-contested congressional races currently held by the GOP in California won by Hillary Clinton in 2016 as the Democrats hope to regain control of the House in the midterm elections. (Photo by Stephen Lam/Getty Images)
WHITMAN, MA - NOVEMBER 6: Republican U.S. Senate candidate Geoff Diehl and his wife KathyJo Boss leave Whitman Town Hall in Whitman, MA after casting their votes on Election Day, Nov. 6, 2018. (Photo by David L. Ryan/The Boston Globe via Getty Images)
Democratic congressional candidate Cindy Axne gets her ballot for the midterm elections at her polling station in West Des Moines, Iowa, U.S., November 6, 2018. REUTERS/Scott Morgan
Democratic congressional candidate running in the 49th district Mike Levin gets an "I Voted" sticker put on by his wife Chrissy after they voted during midterm elections in San Juan Capistrano, California, U.S. November 6, 2018. REUTERS/Mike Blake
Michigan Democratic gubernatorial candidate Gretchen Whitmer shakes hands after voting in midterm election at her polling station at the St. Paul Lutheran Church in East Lansing, Michigan, U.S. November 6, 2018. REUTERS/Jeff Kowalsky
Democratic U.S. congressional candidate Rashida Tlaib points to her 'I voted' sticker after voting during the midterm election in Detroit, Michigan, U.S. November 6, 2018. REUTERS/Rebecca Cook TPX IMAGES OF THE DAY
U.S. Democratic Congressional candidate Jahana Hayes waits in line to fill out her ballot to vote at a voting station during the midterm election in Wolcott, Connecticut, U.S., November 6, 2018. REUTERS/Michelle McLoughlin
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Though Democrats did not win control of the House in the 1998 midterm elections, they were able to stave off losses typically experienced by a sitting president's party, instead picking up four House seats.
The Ways and Means Committee is one of several House panels that could seek to obtain Trump's tax returns, which he has refused to release since his presidential campaign, saying he is under audit by the IRS. According to a Democratic aide the committee — along with the Senate Finance Committee and the Joint Committee on Taxation — has the ability to request a person's tax returns under the tax code.
The chairman could submit a written request to the IRS to provide the information. If the Treasury Department were to deny it, House Democrats would have to decide whether to pursue the tax returns through a legal route. If they are obtained, the chairman would have to designate the panel's members as "agents" to read the returns. They would then have to vote to make the documents public and report them to the full House.