The high stakes primary: why Michigan matters

Given that Michigan awards delegates proportionately, the winner of the primary could earn fewer delegates than the loser. Even so, the contest is a must-win for Mitt Romney and Rick Santorum.

If the polls are any indication, tonight's Michigan primary could be very close. While Mitt Romney and Rick Santorum have been duking it out there for weeks, neither one is likely to win by a wide margin.

And given how Michigan apportions delegates, they may both emerge with about the same numbers (the winner could even receive fewer delegates than the loser).

So why does the Michigan primary matter?

The reality is that both Mr. Romney and Mr. Santorum have a lot at stake – and a lot to lose – with Tuesday's contest.

Fair or not, the media is likely to place disproportionate weight on the outcome – especially since Arizona and Michigan are the first contests held since Santorum won Minnesota, Colorado, and Missouri three weeks ago – and the loser in Michigan is likely to face increased scrutiny on a host of issues.

If Romney wins both states (Arizona will almost certainly vote for him), then it's going to be tougher for Santorum to claim he's the serious contender for the nomination that he claims to be.

Santorum has been struggling in recent weeks, and delivered a lackluster debate performance in Arizona last week. His decision to stake all his bets on social issues seems to be backfiring among some voters, and raising questions about whether he can appeal to women, and to more moderate Republicans and independents.

Also, all the contests he has won so far (except Missouri, whose primary didn't count and where no other candidates campaigned) have been caucuses. Caucuses, where far fewer voters turn out and those who do tend to be the most enthusiastic and represent the most extreme parts of the party, play to Santorum's strengths. But he badly needs to demonstrate that he can win in a straight primary, as well.

Santorum has had trouble appealing to party leaders, whose support he needs to secure in a race this close, and especially given his deficiencies in money, staffing, and organization compared with Romney. And a Michigan win could be pivotal to helping him make his case.

In writing about Santorum's almost total lack of endorsements, even after his big wins in Colorado and Minnesota, the Washington Post's Jonathon Bernstein wrote that:

"... Endorsements are also bets that a particular candidate will do well (it’s rare for there to be any incentive to back a likely loser), and they’re bets made by people with inside information. Senators, governors and members of the House either know each of the serious presidential candidates personally or, at most, are at just one remove from them. The governors of Michigan and Arizona probably have someone they trust who has worked with Rick Santorum and has strong opinions about him. And what they’re hearing, apparently, isn’t anything good for Santorum."

Losing both contests Tuesday may reaffirm in many of those leaders' minds that Santorum's earlier wins were a fluke, and he can't go much farther.

On the other hand, a loss for Romney in his home state will also be a big blow.

Even though he (like Santorum) has sought to temper expectations about his performance there, Michigan is a state that until recently seemed almost certain to go to Romney.

Romney was born and raised in Michigan, and his father was governor there. Losing would raise questions – yet again – about why Romney is having so much trouble delivering victories in states (like Colorado) that on the surface should have been his, despite all his money and organization advantages.

There would be more questions about why Romney struggles in particular in the Midwest, where he has yet to win a state and which may be particularly pivotal in the general election. And about whether he is unable to connect to blue-collar, lower-income voters – a population that may be pivotal in November.

Yet again, his inevitability as nominee would be questioned (look for more talk of a brokered convention), the lack of enthusiasm he generates will be highlighted, and his lack of appeal to more conservative voters will be an issue.

Even with a loss in Michigan, it's not hard to envision Romney still winning the nomination – especially if he can go on to a better performance on Super Tuesday next week. But it will be yet another blow in an already rough month, and could further cripple him in the general election.

Questions about both Romney and Santorum will remain no matter how they perform on Tuesday – but a victory in Michigan, even a narrow one, could go a long way toward giving each of their campaigns a much-needed boost.