Daniel Acker / REUTERS Michele Bachmann (C) greets guests as she arrives for a town hall meeting with Iowa Senator Kent Sorenson (L) in Indianola, Iowa August 12, 2011.

On Wednesday afternoon, state senator Kent Sorenson appeared with Michele Bachmann as the chair of her Iowa campaign. On Wednesday evening, Sorenson was stepping onto the stage at a veterans’ rally to endorse Ron Paul, switching alliances less than a week before the first-in-the-nation caucuses. It’s not the first time Bachmann’s campaign has suffered desertion, but the loss of Sorenson—a longtime, well-connected Hawkeye booster—is especially devastating. Her campaign responded to the news by suggesting that Sorenson had accepted money to make the switch, a charge that Paul’s campaign and a Bachmann aide deny. Amid the drama, TIME spoke to Sorenson about his controversial endorsement.

Why did you decide to endorse Ron Paul?

I believe that we have a clear top-tier race. I believe that is between Ron Paul and Mitt Romney. I believe that the Republican establishment is going to rise up against Congressman Paul. I think we’re seeing that, with the comments that Newt Gingrich made earlier in the week [about not voting for Paul if he were the nominee]. The real crux of the matter is that we’re at a point now where we can elect somebody like Mitt Romney, who is the same as Barack Obama, except maybe a little bit more frugal. He’s a frugal socialist. Or we can elect somebody who’s going to stand up for what our Founding Fathers believed this country was built upon.

(MORE: TIME Poll: Romney, Ron Paul Lead in Iowa)

Was it tough to make this decision?

Absolutely. I love the Bachmann family. I love Michele, but the fact of the matter is it’s a duty I felt like I needed to do for this country. I felt like I had a real opportunity to make an impact in this race. I believe that we need to make sure that Mitt Romney does not win. The fact of the matter is that if Mitt Romney wins in Iowa, it’s going to be a tougher row to hoe down the stretch.

(PHOTOS: Michele Bachmann On and Off the Trail)

When did you make that decision?

The final decision was made about 10 minutes before I went on stage [at the Ron Paul event].

Why isn’t Michele Bachmann in the top tier?

I don’t know, but I’m here to tell you that Ron Paul is in the top two, and we have to make sure he wins.

(MORE: Bachmann Fizzles, Santorums Surges)

What will be the biggest challenge for Paul?

Getting people out to vote for him. We’re going to see a panic with the Republican establishment, but I believe that there are enough good people in the state that are going to go out and caucus for Ron Paul.

Why do you think Paul makes the establishment nervous?

He’s going to do everything he can to make sure the fleecing in this country goes away, and listen, if somebody was trying to keep you from taking money from somebody, don’t you think you would be a little fearful of them? He’s going to be the biggest enemy of crony capitalism.

(MORE: On the Trail with Ron Paul)

How good are Paul’s chances of getting the nomination after Iowa?

I believe that there’s only one organization that was better than [Bachmann’s in Iowa], and now I’m on the best.

How important are the Iowa caucuses?

I believe it’s important. If Ron Paul wins in Iowa, and I believe he will, what it does is launches him to the next phase of the campaign. The people in Iowa, it’s their duty and their obligation to come out and make sure that we do not elect somebody like Mitt Romney. If you value the caucuses process, I can tell you there’s nobody who had honored the caucus process more than Ron Paul. He played in the straw poll, he worked hard, he traveled around the state. He built an organization in every county. I believe that he has run a textbook campaign, and it’s been flawless, and I think he will be rewarded for that.

What will you do to help him on a day-to-day basis?

I’m gonna talk to as many people as I can. I’m going to promote him as much as I possibly can. And I’m gonna caucus for him in my own precinct.