In the Senate, where Republicans will take control from Democrats in January following big gains in the Nov. 4 midterm elections, both parties are expected to vote on Thursday to keep their current top leaders.
Senate Majority Leader Harry Reid of Nevada and Minority Leader Mitch McConnell of Kentucky are expected to switch titles but remain in charge of their conferences, lawmakers and aides said.
Their deputies, Majority Whip Richard Durbin of Illinois and Minority Whip John Cornyn of Texas, also are expected to keep their leadership jobs.
In the Senate, party leaders and whips are elected by a majority vote from the senators of their party. They serve two-year terms that coincide with congressional sessions.
Republican Senators John Thune of South Dakota, John Barrasso of Wyoming and Roy Blunt of Missouri also are expected to stay in their leadership posts, as will Democratic Senators Charles Schumer of New York and Patty Murray of Washington.
In the House, which will remain under Republican control, Republican lawmakers will vote on leaders on Thursday and nominate a candidate for speaker, who will be elected in January by members of both parties.
Current Speaker John Boehner of Ohio, Majority Leader Kevin McCarthy of California, Majority Whip Steve Scalise of Louisiana and Republican Conference Chair Cathy McMorris Rodgers of Washington are running unopposed.
All will serve two-year terms that coincide with the next congressional session.
Representative Raul Labrador of Idaho, one of a small group of Republicans who tried to oust Boehner as the party's leader in 2013, said he had not heard of a similar effort this year.
"I have no interest in doing anything," Labrador said in an interview with Reuters.
House Democrats will elect their leaders on Nov. 18. Current Minority Leader Nancy Pelosi of California and Minority Whip Steny Hoyer of Maryland will run again, and neither is expected to have opposition.
James Clyburn of South Carolina is expected to stay on as assistant Democratic leader, and Xavier Becerra of California as caucus chairman.