The Montana Republican primary for the U.S. Senate race has been called for state auditor Matt Rosendale.

BREAKING: Matt Rosendale wins Republican nomination for U.S. Senate in Montana primary election. @AP race call at 11:33 p.m. MDT. #Election2018 #APracecall #MTprimary pic.twitter.com/xns3Zzk771

— AP Politics (@AP_Politics) June 6, 2018

Rosendale will face Democratic Sen. Jon Tester in November for the Senate seat. Tester is seen as one of the weakest seats that can flip to the Republicans side since President Donald Trump won Montana by a 20-percentage point margin in the 2016 election.

Rosendale's closest competition was retired state Judge Russ Fagg, the choice of Montana's Republican establishment. Money poured into the primary to support Rosendale, who was endorsed by Sens. Ted Cruz (R-Texas), Rand Paul (R-Ky.), and Mike Lee (R-Utah).

Fagg, a fourth-generation Montanan, tried to undermine Rosendale by painting him as a carpetbagger: he had only moved to Montana 20 years ago from Maryland.

Rosendale thanked his supporters on his social media account late Tuesday evening. "THANK YOU, Montana! I could not have won this Primary Election without ALL of you," he tweeted.

"Now we must turn our focus to DEFEATING @JonTester and bringing Conservative leadership back to Washington!" he added.

Tester angers Trump

Tester earned the ire of the president when he made accusations that ultimately cratered Trump's pick to run the Veterans Affairs department. Tester postponed the hearing on Ronny Jackson's nomination when anonymous allegations were presented to the  Senate Committee on Veterans  Affairs. Ultimately, Jackson withdrew his name.

Trump hinted later during a rally that he would help defeat Tester over the controversy.

“Tester started throwing out things that he’s heard. Well I know things about Tester that I could say too,” Trump said to an applauding audience. “And if I said them, he’d never be elected again.”

Here's one of Matt Rosendale's campaign videos from the primary: