Rep. Mac Thornberry is the 6th Texas Republican to announce retirement

Rep. Mac Thornberry (R-Texas) announced Monday that he will not seek re-election in 2020, becoming the 6th Texas Republican — and 19th Republican overall — to retire from the House this term.

Why it matters: Republicans hope to reclaim the House in 2020, but early retirements could complicate that task. Thornberry's retirement means that more than a quarter of Texas' 23 House Republicans will leave at the end of this term, further complicating the party's status in a state that is becoming increasingly competitive for Democrats.

House GOP Texas seats now up for grabs in 2020:

• Rep. Mike Conaway, 11th district
• Rep. Mac Thornberry, 13th district
• Rep. Bill Flores, 17th district
• Rep. Pete Olson, 22nd district
• Rep. Will Hurd, 23rd district
• Rep. Kenny Marchant, 24th district

What they're saying: "With over a year to go, I will continue to represent the people of the 13th District to the best of my ability. Our nation faces many difficult challenges, and none of us can relax our efforts to meet and overcome them, whether at home or around the world," Thornberry, the ranking member of the House Armed Services Committee, said in a statement.

Of note: Thornberry overwhelmingly won re-election in 2018, earning more than 80% of his district's votes.

Go deeper: Shifting demographics could bring Texas into play for Democrats in 2020