Representative Will Hurd of Texas, the only black Republican in the House, announced Thursday evening that he would not seek re-election next year.
He is the sixth House Republican to do so in the past two weeks, and the third from Texas, a wave that has unsettled party leaders as they hope to regain a majority.
Mr. Hurd’s district — which covers a huge stretch of Texas along the southern border, from El Paso to San Antonio — is largely Hispanic and has grown increasingly competitive. A Democrat, Gina Ortiz Jones, came within half a point of unseating Mr. Hurd last year, and the district is likely to be one of Democrats’ biggest targets in 2020.
Mr. Hurd was one of only a handful of Republicans to join Democrats last month in condemning President Trump’s attacks on four freshman Democratic congresswomen, all of whom are women of color.
Representatives K. Michael Conaway and Pete Olson of Texas have also announced their retirements, along with Rob Bishop of Utah, Paul Mitchell of Michigan and Martha Roby of Alabama. And two more — Representatives Susan Brooks of Indiana and Rob Woodall of Georgia — made their decisions earlier in the year.