* Romney clears threshold of acceptability with GOP groups: The big story out of New Hampshire last night is that Mitt Romney — with the help of opponents who have splintered the conservative vote — has now proven himself capable of uniting disparate GOP consistuencies behind his candidacy. The exit polls tell the story:

He was the clear winner among self-identified Republicans and among the often-decisive group of Republicans who consider themselves “somewhat conservative.”

He also was the clear choice among the overwhelming majority of voters who cited economic issues as the principal motivator in their decision and among the one-third of the electorate who said that the ability to beat President Obama was the quality they most sought in a nominee.

And as E.J. Dionne notes, another key finding from the exits shows that Romney is pulling off a remarkable balancing act, successfully presenting himself as all things to all Repblicans:

Voters were asked whether they preferred elected officials who made compromises to get things done, or those who stuck to their principles no matter what...Mitt Romney did about as well in one group as in the other. Whether you liked principled politicians or compromisers, you liked Romney. ..Romney did equally well among social conservatives and social moderates.

In other words, Romney seems to have successfully defined himself as principled and pragmatic; coming across as temperamentally moderate even as he has cleared the threshold of acceptability for enough social conservatives, despite his past apostasy on their core issues. So far, at least.

* Conservative leaders mulling last stand to stop Romney: The question now is whether Romney’s now-proven ability to straddle divides in the GOP will hold when it’s subjected to a much more difficult test: South Carolina. That’s a place where his Mormon faith and corporate past could be more problematic than in Iowa or New Hampshire, conservative and evangelical leaders are set to meet this week to determine whether they can unite behind a single conservative candidate.

The dynamic that’s helped Romney so far — the other candidates continue to split the conservative vote to his benefit — could be particularly important for Romney in South Carolina, given the GOP electorate’s conservative leanings. And this could be the last chance for conservatives to stop him.

* Stop-Romney forces pour huge money into South Carolina: Reid Wilson reports that the pro-Gingrich Super PAC is preparing a massive ad blitz to stop Romney in South Carolina, and check out this key detail about the coming assault on Romney’s Bain years:

Winning Our Future, the Gingrich-backing PAC, will spend a total of $706,000 this week. Sources tell us the PAC is inquiring with South Carolina television stations about the possibility of buying 30-minute — you read that right — slots in order to broadcast a movie that’s critical of Romney’s tenure at Bain Capital.

The anti-Bain documentary will be released later today, so keep an eye out for that. Meanwhile, the pro-Romney Super PAC has booked around $600,000 worth of airtime in the state.

* Will acceptability be enough? As Alex Burns points out, the lackluster turnout in the first two GOP contests raises the question of whether Romney’s mere acceptability to conservatives will be enough against Obama:

To put the GOP nomination firmly within his grasp and start the contest with Obama in a position of strength, Romney will have to do better than acceptability. Republicans want desperately to beat the president. Still, some anxious strategists compare Romney with Bob Dole, the 1996 Republican nominee who failed to capitalize on dislike for President Bill Clinton because he was a dull and unappealing character himself.

Turnout in the early Republican nominating contests could be a warning sign for Romney: the participation rate in Iowa barely exceeded the state’s 2008 mark, when many GOP voters were disaffected and depressed. New Hampshire officials projected record turnout in Tuesday’s primary, but exit polls showed about two-fifths of the voters were non-Republicans who crossed over to participate.

Steve Benen has more.

* Romney leaves New Hampshire damaged for general election: Despite his strength, Ron Fournier notes that New Hampshire may have damaged him over the long term, cataloguing all the bad missteps he committed in New Hampshire that will make it easier for the Obama team to cast Romney as a “cold-hearted phony.”

Taken all together, they are a striking series of political errors that all serve the same storyline, and the DNC has already doubled down it in a new Web video it released this morning.

* The arc of Romney’s story: Relatedly, don’t miss Philip Rucker’s look at the arc of Romney’s privileged life and how that dovetails with his inability to shake his aura of inauthenticity.

* Obama reelect reality check of the day: A new Quinnipiac poll finds Mitt Romney edging Obama in the key swing state of Florida among registered voters, 46-43, though that’s within the margin of error.

The worrisome numbers for Obama are his 42-54 approval rating and his weakness among men (he loses them 40-52), seniors (39-53), and those without college degrees (31-56). Those are all key demographics among which Obama has suffered losses on a national level that he needs to reverse before November.

* Romney developing pushback to Bain attacks: Peter Wallsten and Karen Tumulty point out that Romney has shifted his language to better fend off the attacks on his corporate past:

Romney has sharpened his rhetoric, now regularly borrowing a line from Sarah Palin to rail against “crony capitalism,” a term that refers to companies that use political connections to score government aid and tax breaks. Such language is a decided departure for Romney, who has forged close ties with corporate America but now must reconcile his image as the chamber-of-commerce candidate with the anti-Washington fervor animating much of his party’s base.

The use of the term “crony capitalism” seems designed to cast Romney as an antagonist of corporate power, at least when it comes to influencing government, among voters who see the nexus of Wall Street and government as the problem.

Key footnote: Romney supports doing away with all limits on the size of contributions to campaigns.

* Time for a great debate about what we want America to be: As Jonathan Cohn notes, the ideological battle lines are now drawn, and Americans face a very big choice about their country’s future.

* And Occupy Wall Street has its own Super PAC: The National Memo has the interesting tale of a former prison guard who has formed a Super PAC to push Occupy issues in Congress, and has even registered as a lobbyist to do the same, which may foreshadow a broader effort by the movement to influence the traditional political process.

What else?