WASHINGTON — An early wave of Republican retirements in the U.S. House of Representatives is bolstering Democrats’ chances of holding the majority in 2020 and flipping key seats in GOP strongholds like Texas.

Texas Rep. Kenny Marchant on Monday became the latest Republican to announce he’s not running for re-election, joining 10 House GOP colleagues who already have done so. He’s the fourth Republican abandoning a Texas seat at the end of his term, and his district is one of several in the state where demographic and political shifts are favoring Democrats.

A spike in Republican retirements in 2018 gave Democrats the chance to win some House seats that otherwise might have been out of reach. Democrats managed to flip 40 GOP-held districts, mostly in suburban areas where women and college graduates have soured on President Trump.

While there probably won’t be as many Republicans retiring in 2020, there likely are still more to come as the GOP faces the prospect of Democrats maintaining or expanding their 235 to 197 advantage in the House as both parties also contest control of the Senate and White House.

“Republicans aren’t feeling optimism about winning back the majority,” said Dave Wasserman, House editor of the nonpartisan Cook Political Report.

At least four of the GOP-held seats now open are considered competitive. That includes those held by Marchant and two of his fellow Texans, Pete Olson in suburban Houston and Will Hurd, whose district stretches from the outskirts of San Antonio almost to El Paso and is most likely to flip to a Democrat, according to the Cook report. Rob Woodall’s seat in the outer suburbs of Atlanta also is rated as a toss-up.

Marchant’s announcement was greeted with a gleeful statement from the Democratic Congressional Campaign Committee.

“In the last two weeks we got a whole new term in the American political vernacular: the “TEXODUS!”

The other Republicans retiring gave a variety of reasons, personal and professional, for leaving the House. Reps. Bradley Byrne of Alabama, Greg Gianforte of Montana and Rob Bishop of Utah, for example, are considering or planning runs for higher office. Martha Roby of Alabama and Susan Brooks of Indiana, who has been in charge of the GOP’s candidate recruitment for 2020, cited personal choices. Paul Mitchell of Michigan said frustration with Washington politics played a role in his decision.

Marchant didn’t spell out his precise reasons for retiring, saying, “I am looking forward to finishing out my term and then returning to Texas to start a new chapter.”

House Republican leader Kevin McCarthy of Bakersfield and his lieutenants dismiss the idea of a significant GOP exodus. He said on “Fox News” this week that some of the retirements are natural, as senior Republicans approach the typical length of a congressional career, or know their time in top committee posts are up because of term limits.

Billy House is a Bloomberg News writer.