BILLINGS, Mont. (AP) — Montana Republican Congressman Matt Rosendale said Thursday he is dropping his bid for the U.S. Senate less than a week after he got into the race on the same day that former President Donald Trump endorsed his opponent.

Rosendale, a hard-line conservative, said in a statement that with Trump’s endorsement of fellow Republican Tim Sheehy and with a lack of resources, “the hill was just too steep.”

The move comes after leading Republicans had backed Sheehy as the party’s best chance to topple three-term Democratic Sen. Jon Tester as part of their strategy to take control of the Senate.

Rosendale’s announcement last Friday that he would challenge Sheehy in the Republican primary set off a potential matchup between the conservative firebrand and former Navy SEAL Sheehy, who was encouraged to run by Montana Sen. Steve Daines — the chair of the National Republican Senatorial Committee.

Rosendale said he would be able to challenge Tester despite losing to him in 2018.

“I’ve won two elections since then,” Rosendale, 63, told reporters after filing paperwork Friday to formally enter the race. “And the most important thing is that my name ID and my trust factor is elevated dramatically. People know who I am.”

While several conservative state lawmakers cheered Rosendale’s filing, Daines issued a statement saying: “It’s unfortunate that rather than building seniority for our great state in the House, Matt is choosing to abandon his seat and create a divisive primary.”

It’s not clear if Rosendale will seek re-election to his U.S. House seat following Thursday’s announcement. Several other Republicans have already announced their intentions to enter that race, which is in a solidly GOP district.