After less than one week as a declared candidate, Republican Representative Matt Rosendale is suspending his bid for U.S. Senate in Montana on the grounds that winning Republican primary was next to impossible without the endorsement of former President Donald Trump, who won the state by sixteen points in 2020.

The likely 2024 presidential nominee had humiliated Rosendale shortly after the congressman announced his Senate campaign Friday morning by endorsing his then-rival, businessman and ex-Navy SEAL Tim Sheehy, that afternoon.

“By my calculations, with Trump endorsing my opponent and the lack of resources, the hill was just too steep,” Rosendale told Politico, who first reported the news Thursday afternoon. “I spoke with Sen. Daines earlier this week and we both agree that this is the best path forward for Republicans to regain the majority in the U.S. Senate,” Rosendale added, referring to the Montana senator Steve Daines, who had recruited Sheehy and endorsed him early on in the primary.

A campaign adviser to Rosendale’s short-lived Senate campaign confirmed that polling suggested the odds of surviving a statewide race without Trump’s endorsement looked grim.

Rosendale ran unsuccessfully as Republicans’ senate nominee against Democratic senator Jon Tester in 2018 and lost to him by three and a half points. Without Rosendale in the primary this cycle, Republicans can avoid a costly and messy primary and can focus their time and resources on winning the general election.