The 2018 midterm elections on Tuesday, Nov. 6, will give President Trump his first chance to defend the Republican Party's Senate and House majorities. Here's a running list of the GOP senators and members of Congress who have announced they won't be seeking re-election:

Senate

Sen. Bob Corker, R-Tenn.

  • After tangling with President Trump, including questioning his "stability" and "competence," Corker put an end to speculation and announced he would not be running again in 2018. Corker and Trump have since engaged in multiple scraps on Twitter, Corker calling it "a shame the White House has become an adult day care center" and Trump saying Corker "couldn't get elected dog catcher."

Sen. Jeff Flake, R-Ariz.

  • Flake confirmed his decision in a Senate floor speech in October and condemned the current state of politics, specifically President Trump, as one of the main reasons he's deciding to step aside.

Sen. Orrin Hatch, R-Utah

  • Hatch's retirement creates an opening for former Republican presidential nominee Mitt Romney to mount a Senate bid. Hatch kept Utah Republicans on edge for months before announcing his decision: "Every good fighter knows when to hang up the gloves," Hatch said.

House

Rep. Joe Barton, R-Texas

  • Barton announced he will not seek re-election after a naked selfie and his private Facebook messages were made public.

Rep. Charlie Dent, R-Pa.

  • Dent, a centrist Republican, announced in September that he'd decided against running for re-election after consulting with family and advisers. Pennsylvania state Rep. Justin Simmons had announced he would challenge Dent in the primary.

• Rep. John Duncan, R-Tenn.

Rep. Blake Farenthold, R-Texas

  • Farenthold announced in December he would not run for re-election amid allegations of sexual misconduct and "abusive" behavior from former staff members.

Rep. Rodney Frelinghuysen, R-N.J. Chairman of the House Appropriations Committee

  • Frelinghuysen was a key target of Democrats heading into November. He didn't cite a specific reason for retiring, but encouraged younger people to try public service.

Rep. Bob Goodlatte, R-Va. Chairman of the House Judiciary Committee

Rep. Trey Gowdy, R-Texas Chairman of the House Oversight and Government Reform Committee

  • A combative and often headline-grabbing Republican firebrand, Gowdy said he enjoys "our justice system more than our political system," and will be retiring from Congress to return to the courtroom.

Rep. Gregg Harper, R-Miss. Chairman of the House Administration Committee

  • After his first election in 2018, Harper said he "never intended for this to be a career, and it will soon be time for another conservative citizen legislator to represent us."

Rep. Jeb Hensarling, R-Texas Chairman of the House Financial Services Committee

  • Speculation had been building that Hensarling would not seek re-election after getting termed out of the House Financial Services chairmanship. Unlike the centrist Republicans who have announced their retirement, Hensarling sees eye to eye with the Trump administration on most issues.

Rep. Darrell Issa, R-Calif.

  • Issa was expected to be among the most endangered GOP lawmakers in 2018. He won re-election in 2016 by a slim margin and his San Diego district is likely smarting over the GOP tax reform bill that will limit state and local tax deductions, which are significant there.

• Rep. Lynn Jenkins, R-Kansas

• Rep. Sam Johnson, R-Texas

Rep. Frank LoBiondo, R-N.J.

Rep. Tim Murphy, R-Pa.

  • Publicly pro-life, Murphy said he would not be running for re-election in 2018 after it was revealed that he had asked his mistress to have an abortion.

Rep. Ted Poe, R-Texas

Rep. Dave Reichert, R-Wash.

  • Reichert faced tense townhall crowds during the August recess, and announced upon returning in September that he had decided "this will be my last term." A number of Democrats were already preparing to try to challenge him. The Democratic Congressional Campaign Committee celebrated afterward that "clearly, Congressman Reichert saw the writing on the wall."

Rep. Ileana Ros-Lehtinen, R-Fla.

  • Cuban-American and the first Hispanic woman elected to Congress, Ros-Lehtinen announced back in April 2017 that she will retire at the end of her current term. Speaker Paul Ryan afterward called her "a force." She has clashed with President Trump on transgender issues, deportations, and his travel ban.

Rep. Ed Royce, R-Calif. Chairman of the House Foreign Affairs Committee

  • Royce announced he would retire rather than seek re-election days after President Trump tapped his wife for a senior position in the State Department, one overseen by the Foreign Affairs Committee that Royce chairs. Democrats plan to make an aggressive push to win the seat after Hillary Clinton carried the district in 2016.

Rep. Bill Shuster, R-Pa. Chairman of the House Transportation and Infrastructure Committee

  • Shuster told the Washington Examiner exclusively that he would not seek re-election in 2018 in order to concentrate full-time on getting an infrastructure package passed into law with President Trump.

Rep. Lamar Smith, R-Texas Chairman of the House Science, Space, and Technology Committee

  • Smith made a name for himself as head of the House Science, Space and Technology Committee, especially in the last Congress when he often questioned the Obama administration's focus on climate change. In a letter to supporters, he said he has "one new grandchild and a second arriving soon. And I hope to find other ways to stay involved in politics."

• Rep. Pat Tiberi, R-Ohio

• Rep. Dave Trott, R-Mich.

  • A centrist Republican who has criticized President Trump, Trott announced in September after some speculation that he would not seek a third term.

Updates will be added.