Talk about fairweather friends. Iowa state Sen. Kent Sorenson (R), who was Minnesota Rep. Michele Bachmann’s state campaign chairman, endorsed Texas Rep. Ron Paul Wednesday night.

At a rally in Des Moines, Sorenson told the crowd, “We’re going to take Ron Paul all the way to the White House.”

He did not tell Bachmann of his decision until he was en route to the Paul rally, billed as an event for veterans.

“This is hard,” he said of his decision to leave Bachmann, explaining that he felt obligated to defend Paul against the Republican establishment. He elaborated in a statement, saying he felt Paul was the most conservative candidate who had a realistic shot at defeating former Massachusetts governor Mitt Romney.

Sorenson added that Paul campaigned for him during his state Senate race last year.

“I thought it was my duty to come to his aid, just like he came to my aid during my Senate race, which was a very nasty race,” he said.

The state lawmaker attended a Bachmann event just four hours earlier and declined to speak to the crowd, citing dental work. He was one of her earliest supporters in the state.

Paul’s campaign touted the endorsement in a press release, saying that Sorenson’s resignation from Bachmann’s team was effective immediately.

Rachel Weiner has more at The Washington Post's blog with Sorenson's full statement to the press.