It is usually assumed that the invisible primary ends with the Iowa Caucuses, when the party rank-and-file begin to have their say. But thanks to an exceptionally chaotic and unpredictable pre-caucus period, the central dynamic of the invisible primary—Mitt Romney’s wooing of conservatives skeptical of him—has been extended. And now it’s reached a new phase: The internal struggle among conservative opinion-leaders about when it will prove necessary to throw in the towel and settle for Romney.

The most underreported feature of the contest so far is that most conservatives have already reconciled themselves to Romney as the nominee. They may prefer someone else, and in pursuit of that preference—or to keep ideological pressure on Romney—they may continue to raise alarms about the front-runner’s record, positions, or general-election strategy. But it is exceedingly difficult to find a significant conservative figure who has not already pledged to back Mitt fully if he’s the nominee.

As a result, there will be no last-ditch rightwing crusade to deny Romney the nomination. Nor will a discouraged base threaten to throw the general election to Obama. Instead, you can expect to see an increasingly public debate on the right about the costs and benefits of further resistance, until an eventual surrender.

There are powerful arguments for throwing in the towel early, though the factor most often pointed to by the Beltway commentariat—Mitt’s superior electability—is not necessarily the strongest. Yes, some conservatives (along with most Democrats) have embraced the conventional wisdom that successful candidates must be able to move to the center to win and deemed Romney the obvious choice on electability grounds. But these are people largely already in his camp. Though it’s sometimes hard for political pros to accept, most conservatives simply don’t buy the CW. They actually believe what they have been repeatedly saying since they pulled the GOP hard right after two straight general election debacles: This is a conservative country whose electorate responds best to a clear, consistent conservative message. The 2010 results confirmed that in their minds—and neither political scientists nor polls nor pundits can persuade them otherwise.

So if electability is not a clinching argument for getting on board the Romney Express, what might be? The main temptation for conservatives to call it a day is the strong likelihood that an extended nominating contest will become so nasty, divisive, and cash-draining that it will damage the ticket far more than any “base” misgivings about Romney might. Even as Republicans celebrate the general election advantage they expect from Super-PACs, their lethal power in intra-party battles is becoming plainer every day, and now that Gingrich has foresworn positive campaigning, none of the survivors can be expected to play nice.

Just as importantly, “true conservatives” have doubts and divisions about the ideological reliability of Mitt’s surviving rivals. Santorum is regarded by some as an Washington insider and Big Government Conservative. Newt’s heresies were amply aired by those attack ads in Iowa. And Perry, the closest thing to a consensus “true conservative” candidate, greatly upset believers with his position on immigration.

And so, conservative leaders may well be asking themselves: Is the dubious value of nominating Santorum or Gingrich or even Perry instead of Romney worth the risk of creating the foundation for an Obama campaign assault on the eventual winner as a flip-flopping opportunist with the character of a feral cat?

Possibly not. Currently the most important residual reason for continuing the anti-Romney resistance is the feeling that he hasn’t yet paid sufficient deference to movement conservatives (even though, ironically, he was their candidate four years ago) or made sufficient promises to make their priorities his own. These are concerns that should be able to be finessed. There may well be furious behind-the-scene negotiations going on to ensure that Mitt doesn’t emulate his new supporter John McCain by getting all “mavericky” in the general election or implicitly triangulating against the Right. And it could culminate in a sort of political Groundhog Day, when a particularly powerful opinion leader signals the troops to shorten or extend the nominating contest (though the leader best positioned to do so, Sen. Jim DeMint, has indicated he does not intend to make an endorsement at all.)

So the fight could go on for a while, but not for an extended period (unless Romney does something uncharacteristically stupid, or Rick Perry achieves a complete resurrection). In head if not heart, conservative elites have already given their hand to Mitt, and much of what’s going on at the present is simply a matter of maintaining appearances and executing a solid pre-nup.

Ed Kilgore is a special correspondent for The New Republic.