The Romney ceiling: Can he ever win over conservatives? Does he need to?

What does Mitt Romney have to do to win his party’s base? And does he even need to?

As the former Massachusetts governor’s eventual nomination as the GOP presidential candidate becomes ever more likely, there seems to be an increased desperation among those conservatives willing to ally themselves with anyone but him.

The momentum has swung from Michelle Bachmann to Rick Perry to Herman Cain to Newt Gingrich as candidate after candidate flies high, only to crash. (Ron Paul has his own coterie of intensely loyal supporters, but also has a hard time winning the GOP base.)

So, why not Mitt?

Media speculation about the search for an “anti-Romney” candidate has been rampant for months, but polling suggests the idea isn’t just a fabrication of pundits looking for something to talk about.

Despite his success – and his consistency throughout the campaign – Mr. Romney seems to have hit a ceiling of about 25 percent in virtually any poll.

A recent Bloomberg News poll of likely Republican caucus-goers in Iowa suggests one reason, with 58 percent of those polled saying they would rule out any candidate who had favored a mandate to buy health insurance.

There was more opposition on that score than on any other point the voters were asked about, including how they felt about a candidate who had been married three times and had extramarital affairs (48 percent said they’d rule him out), or who had been accused of sexual harassment (30 percent).

To many core Republicans, Romney can’t shake his image as a liberal-to-moderate Northerner – a former GOP governor of a Democratic state who used to favor abortion rights and pushed through a health-insurance mandate that was the model for Obama’s.

One conservative blogger recently called his run “a hostile takeover of the conservative movement.”

The fact that he’s a Mormon only makes him more suspect. (Romney’s faith has been attacked directly by at least a few conservatives, including intellectuals like Christopher Hitchens and prominent pastors like Robert Jeffress.)

All of which seems to make some Republicans more willing to embrace a thrice-married philanderer (Mr. Gingrich) than Romney. At least, the former House Speaker seems the current choice of the anti-Romney Republicans. A Fox News poll released Wednesday shows him doubling his support in the past three weeks to 23 percent, essentially tying Romney (22 percent) for the lead, and several other national polls now put him at or near the top.

None of this is news to Romney. Despite moving ever farther to the right, he knows his challenges with conservative Republicans.

It’s one reason he seems to be making less of an effort in Iowa (where committed caucusgoers tend to be further to the right), despite recently earning the censure of Iowa’s powerful governor for passing up events like this weekend’s Christian conservative candidate forum and the governor’s birthday fundraiser.

“I think he’s making a big mistake by not coming here … and spending more time,” Gov. Terry Branstad said Wednesday at a Politico-sponsored forum.

But does it really matter?

So far, Romney’s strategy seems to be working, as one after another of his opponents self-destructs. It’s hard to picture any of them, at this point in the campaign, rallying enough support to win the nomination, however much the conservative wing of the party dislikes Romney.

One irony to all that opposition: Repeated polls suggest that Romney has a far greater chance than Gingrich, Mr. Perry, or almost any other GOP candidate of beating President Obama in the general election.

Which, according to most of the Republican base, is their top goal.