When the tea party Republican Kent Sorenson left Michele Bachmann for Ron Paul, it was clear that the tea party has two opponents in this presidential election: President Obama, and Mitt Romney.

Sorenson, a state senator in Iowa, said on Wednesday that Paul is the "most conservative" of the top-tier Republican candidates, and that he's a better bet to beat Romney, the ex-governor of a liberal state who has struggled to win over the tea party. For some tea party members, Sorenson's switcheroo is the echo of a desire in the movement to nominate a Republican other than Romney, who has the best chances of winning the GOP primary.

"There is a huge anti-Romney sentiment," said Judson Phillips, the founder of Tea Party Nation, who endorsed Newt Gingrich in September.

"The Iowa tea party movement is opposed to Romney because we just believe that he's probably big government and more of a liberal Republican, although he has some conservative values and he's a good man," said Charlie Gruschow, a tea party activist in Des Moines who advises Gingrich's campaign.

The biggest hurdle Romney faces in courting the tea party is trying to shake off his health care record in Massachusetts, which the White House has said was a model for ObamaCare. While Romney has held on to a loyal group of supporters in recent months - about one-quarter of GOP voters - conservatives have rotated through the rest.

Romney supporters say that, once he's the nominee, Republicans will coalesce around him. Asked if she could see the tea party coming together to support Romney, Amy Kremer, the chairwoman of the Tea Party Express, said, "I don't know where the tea party's going to go."

"I think it's going to be a very bumpy ride, and it could get pretty ugly," said Kremer, who hasn't endorsed a candidate yet.

But Judson said that surveys of Tea Party Nation members show that as many as half of them say they'll refuse to vote for him in a general election because he's too "liberal."

Not all tea party members feel that way.

"I don't particularly want to see Romney, but … whether it's Gingrich or Romney or whoever it is, we have got to get behind whoever it is," said Jack Staver, a tea party activist in Atlanta.

Romney has shown confidence lately in Iowa, raising expectations for a strong finish against his chief opponent, Paul. And even after Sorenson's endorsement, tea party leaders say they're still skeptical of Paul's outside-the-mainstream positions.

"The only thing nuttier than Kent Sorenson's comment is Ron Paul's campaign," Phillips said. "Ron Paul has no chance of beating Romney, and he has no chance of beating Obama."

The latest CNN/TIME/ORC poll from Iowa shows Romney barely leading Paul among Republicans, 25 percent to 22 percent.