Mitt Romney won Michigan. Great — even if it was by a measly three points. He had no other choice. Romney either had to win his home state or see his presidential ambitions go poof! Looking at the exit polls he did well where he needed to. And just as in other contests, Romney won the overwhelming majority of the votes of folks who view him as the one who can defeat President Obama. At 32 percent, this was the most important quality listed by those surveyed. Romney snagged 61 percent of that vote.

But there’s danger in them there numbers. Notably further confirmation of the enduring lack of enthusiasm this Republican primary season for the field of candidates. The problem for Romney and the next Republican nominee was on display in a set of exit poll stats that MSNBC’s Tamron Hall showed during primary coverage last night:

                               2012      2008
DEMOCRAT          9%    7%
INDEPENDENT       31%      25%
REPUBLICAN           60%      68%

   Rick Santorum’s robo-calls to Democrats fell on deaf ears, it appears. Even though there was a 2 percent uptick of Democrats voting in the Republican primary over 2008, “the difference isn’t even statistically significant compared to four years ago,” as The Post’s Aaron Blake notes.

But here’s the number that caught my eye. The number of self-identified Republicans dropped by 8 points compared with 2008.

As the Los Angeles Times reportedthis month, “The decline in turnout has been consistent from the first contests in Iowa and New Hampshire, with the number of self-identified Republican voters falling everywhere but South Carolina.”  The story goes on to say that “[t]urnout has fallen in every contest since” that Jan. 21 contest:

. . . down 14% in Florida, 26% in Nevada, 6% in Colorado, 23% in Minnesota and 58% in Missouri.

Still, Romney won. But it’s a tainted win. That a Republican born and raised in Michigan by a father who was the state’s governor could only eke out a three-point victory with lower Republican participation is nothing to crow about. It only compounds the trouble he faces in Ohio.

Update, 2:00 p.m.: The statistics on the percentage of self-identified Republicans — 68 percent in 2008, but 60 percent yesterday — were correct. But the raw numbers upon which they are based tell a slightly different story.

According to The Post’s polling director Jon Cohen, that 68 percent in 2008 was of 869,169 voters. Last night’s 60 percent was of 1 million voters. Therefore, there was an increase of nearly 9,000 Republican voters yesterday over 2008. So, essentially, turnout was flat, which should still be concerning to Romney, considering he is a born-and-raised Michigander and there is a burning desire in the GOP to boot Obama from the White House.