If Mitt Romney loses today in Michigan, it could throw the GOP primary into chaos and force a battle that extends well past Super Tuesday, March 6th. But most polls show that Romney will narrowly win in the state, where he has deep ties.

However, even if Romney does win, strategists in both parties will be closely watching tonight’s results to see whether he continues to be dogged by a vulnerability that could have serious ramifications in the general election: His White Working Class Problem.

New Post polling out this morning underscores the depths of his difficulties. It finds that Romney’s favorability rating nationally is at just 37 percent among conservative Republicans and independents with incomes of under $50,000, versus 40 percent of them who view him unfavorably. Rick Santorum performs better with this group, but since Romney is still the likely nominee, this isn’t really about Sanorum; it’s about Romney’s long term prospects.

The Post polling team provides more numbers: Among non-college whites across the board, Romney’s favorability rating is also at 37 percent. (Obama’s favorability among these voters is the same; yet a competitive Republican is supposed to have a very significant advantage over a Democrat in presidential elections.) Even worse, Romney’s numbers among independents across the board are an abysmal 29-44, down from 37-40 earlier this month.

And so strategists will be watching to see how Romney fares among these voters in today’s primary, which is an open one in which independents can participate. If he’s the nominee Romney will have another chance to introduce himself to these voters nationally on more favorable terms. But these trends have to be alarming to GOP leaders.

* Right-leaning writers worried about Romney: Indeed, don’t take my word for it. Michael Gerson gives voice to rising GOP worry about Romney’s propensity for saying things that alienate these voters:

These blunders not only reinforce a traditional Republican weakness, they threaten to diminish a large Republican advantage — Barack Obama’s dramatic disconnect with blue-collar whites. The candidate who talked of small-town Americans as clinging “to guns or religion” lost white working-class voters by 18 points in 2008. In 2010, congressional Democrats lost the same group by 30 points. A similarly dismal performance by Obama in 2012 would open vast blue portions of the electoral map to Republican raids.

Romney may be the only candidate capable of herding working-class voters back toward the president.

And it’s true that the alienation of these voters from Obama remains a problem. But Romney may not be able to exploit it to the degree the GOP needs. Meanwhile, Ari Berman gets the Dem perspective on this from pollster Stan Greenberg.

* Obama to press auto bailout as Michigan votes: The President will be far from the Wolverine State today. But in his address to the United Auto Workers in Washington, he’ll be making a case that’s all about Michigan, framing his support for the auto-bailout — and Romney’s colossal wrongness about it — as representative of the larger ideological contrast that will drive the 2012 presidential election.

* What happens if Romney does lose Michigan? GOP pollster Matthew Dowd spells it out:

“If Rick Santorum wins tonight it’s the equivalent of a 9.0 on a Richter scale. I mean it is going to shake Washington, it’s going to shake Republican establishment it’s just going to shake things to their very core. And I think what you’re going to see are the conversations that have been going on behind quiet doors saying we need another candidate in this race.”

* Could Dems make difference in Michigan? Dems and liberals (and Santorum) have been urging Michigan Dems to get out and vote for Rick, and as far fetched as it might seem, Public Policy Polling finds evidence that it’s not out of the realm of possibility that this could make a difference today.

* Too close to call in Michigan: Nate Silver’s forecasting model, which had previously predicted a Romney victory, now finds that it’s too close to call.

Bottom line: “If Mr. Romney loses, you’ll begin to hear questions asked like why Mr. Romney has had trouble closing out victories, whether his organizational strengths are overrated and whether voters are souring on Mr. Romney as they get to know him better — not to mention all the chatter about late-entry candidates and brokered conventions.”

* Romney’s love-hate relationship with crossover voting: Romney has professed outrage over Santorum’s appeal to Dems, but it turns out Romney himself crossover voted in a 1992 Dem primary, openly admitting he did so to swing that year’s Senate race.

* Dems raise Michigan expectations for Romney:The DNC’s memo pre-framing tonight’s Michigan results focuses almost entirely on Romney. Even if he wins, it argues, the huge amount of money necessary to eke out a narrow victory in his home — combined with his lurch to the right, which will alienate independents — confirms his weakness as a general election candidate and the toll the primary has taken on him.

* Dems think they have edge in contraception fight: Dems will hold a vote in the Senate this week on the Blunt amendment to undo Obama’s birth control coverage mandate, and they are proceeding from the assumption that they hold the political upper hand. Messaging chief Chuck Schumer says the GOP will sustain “lasting damage” among independents, a sign that Dems want this to be a wedge issue in this year’s elections.

Republicans continue to describe Obama’s measure (which exempts religious institutions) as an assault on religious liberty, because they want to drag this battle on to old culture war turf.

* And the battle for Senate remains deadlocked: Paul Kane has a nicely reported piece on the state of play in the battle for the Senate: The recovering economy, combined with the GOP’s new focus on social issues, makes it unlikely that Republicans will make the kind of expected big gains that would break Senate gridlock, even if they take back the majority.

Related outstanding question: What kind of filibuster reform might Republicans undertake if they do win the majority?

What else?