WASHINGTON — Monday’s announcement that another Republican congressman is retiring highlights the GOP’s struggle to win the House majority next year and the shifting political leanings of Texas.

Yet the arc of the state’s demographic and political changes is such that Trump remains the favorite to win the state’s coveted 38 electoral votes next year. And GOP Sen. John Cornyn, a three-term Senate veteran who’s raised a daunting cache of campaign money and has plans to raise more, may prove difficult for Democrats to topple.

Rep. Kenny Marchant, an eight-term lawmaker from the Dallas-Fort Worth suburbs, said Monday he won’t seek re-election in 2020. That made him the 11th GOP representative to so far say he’ll step aside — compared to just three Democrats.