Scott Walker throws his support to Ted Cruz a week before the crucial Wisconsin primary

Wisconsin Gov. Scott Walker endorsed Sen. Ted Cruz of Texas Tuesday, a week before his state votes in a key GOP primary.

Walker, in an interview with WTMJ's Charlie Sykes, said Cruz is in the best position to beat former Secretary of State Hillary Clinton in the fall's general election.

He added that he wanted to be "for," not "against" someone.

GOP frontrunner Donald Trump conceded in a tweet Monday night that there was "no way" he'd ever receive an endorsement from Walker.

"After the way I beat Gov. Scott Walker (and Jeb, Rand, Marco and all others) in the Presidential Primaries, no way he would ever endorse me!" he wrote.

In the last two Wisconsin polls released, Cruz was ahead of Trump by slim margins, per RealClearPolitics. Many in the "Never Trump" movement see Wisconsin as a last stand to stop the party's frontrunner from clinching the nomination.

Walker was considered one of the stronger 2016 GOP presidential contenders when the campaign heated up last summer. But Walker and other candidates struggled to gain traction as Trump surged to the top of the field.

Last September, Walker ultimately became the first of the 17 Republican candidates to drop out of the race.