In this July 16, 2019, file photo, Rep. Jim Sensenbrenner, R-Wis., ranking member of the House Judiciary antitrust subcommittee, speaks during a House Judiciary subcommittee hearing with representatives from major tech companies on Capitol Hill in Washington. (Patrick Semansky/AP)

Rep. F. James Sensenbrenner Jr., who has served in Congress for 40 years and is the second-most senior House member, announced Wednesday that he won’t seek reelection, joining more than a dozen Republicans heading for the exits.

The 76-year-old Wisconsin lawmaker becomes the highest-ranking Republican to say he would step down at the end of his term, part of a growing wave of retirements that suggest GOP pessimism about regaining the House majority in 2020.

Sensenbrenner has been a mainstay on the House Judiciary Committee, where he served during President Clinton’s impeachment in January 1999 and was one of 13 House impeachment managers who tried the case in the Senate.

He also served as the panel’s chairman in the past decade and has headed the Science Committee.

“For 40 years I have held over 100 town hall meetings each year; I have helped countless individuals when they have encountered difficulties with the federal government; I've taken 23,882 votes on the House floor; been the lead sponsor or co-sponsor of 4299 pieces of legislation; ushered 768 of them through the House for passage, and watched as 217 of them have been signed into law by six different presidents,” Sensenbrenner said in a statement. “I think I am leaving this district, our Republican Party, and most important, our country, in a better place than when I began my service.”

Sensenbrenner was instrumental in securing passage of the Patriot Act, which gave the government more tools to combat terrorism after the Sept. 11 attacks.

Republicans will be favored to hold the Wisconsin seat as Donald Trump handily won the district by 20 percentage points in 2016 and Sensenbrenner rarely had a tough race. The congressman, who hails from a wealthy family, is a known as an avid lottery player and has won it at least three times.

Sensenbrenner joined two of his colleagues in calling it quits on Wednesday alone, making him the 16th House Republican to announce he would not seek reelection in 2020. By contrast, only four Democrats have announced plans to voluntarily exit the chamber, which their party controls, with Rep. Susan A. Davis of Southern California adding her name to that list with an announcement Wednesday.

In addition to Sensenbrenner, Rep. Bill Flores (Tex.), the former chair of the conservative Republican Study Committee, also announced plans to retire at the end of his term. The retired oil and gas executive who would also serve on the House Energy and Commerce Committee first won his seat by defeating a longtime Democratic incumbent. His Central Texas district has since also become reliably Republican.

Last year, Flores prevailed with nearly 57 percent of the vote. Flores wants to spend more time with his family and resume private-sector business activities, he said in a statement. He became the fifth GOP lawmaker from Texas to retire.

“After much prayer over the past few days and following conversations with my wife, Gina, during that time, I have decided that my current term will be my last,” Flores, 65, who was first elected in 2010, said in a statement.

Several of the Republican retirements have been in increasingly competitive districts; in three of them, GOP incumbents won reelection by fewer than five percentage points in 2018. But others are in safer districts, like Sensenbrenner’s and Flores’s.

Davis has represented her Southern California district since 2001. In a letter to her constituents, Davis did not say why she was leaving but expressed a desire to live and work in San Diego after 20 years of commuting cross-country. She wrote that she had “struggled to make this very difficult decision.” 

“This is tough for me. There are always compelling issues and challenges that have encouraged me to pursue each new election cycle,” Davis wrote. “Most touching has been the appeals to stay on and go yet another round with the hope that I would always be your representative. It doesn’t get any better than that!”

Davis’s district is solidly Democratic — Hillary Clinton won it over Trump in 2016 by 35 points — so there is little risk to her party that her leaving would result in a Republican pickup. 

Other Democrats who have announced their retirements are Reps. José E. Serrano (N.Y.), David Loebsack (Iowa) and Ben Ray Luján (N.M.), who is running for the Senate. 

Paul Kane contributed to this report.