According to SCOTUSBlog’s conversation this morning, we’re not expecting the actual ObamaCare decision until 10:15 am ET at least, so let’s focus on the horserace for that brief period.  NBC and Marist have teamed up to do some presidential polling in key swing states, which now includes … Michigan?  A succession of polls show that Mitt Romney has surprisingly tied the Man Who Singlehandedly Saved The Auto Unions, er, Industry — and so does the latest NBC/Marist poll:

A new round of NBC News-Marist polls shows President Barack Obama and Republican Mitt Romney running almost neck-and-neck in three key battleground states, with Obama holding a slight advantage in Michigan and North Carolina, and the two candidates tied in New Hampshire.

In Michigan, Obama is ahead by four percentage points among registered voters, including those who are undecided but are still leaning toward a candidate, 47 to 43 percent.

In North Carolina, the president gets 46 percent to Romney’s 44 percent, which is within the survey’s margin of error.  And in New Hampshire, the two men are tied at 45 percent each.

A few months ago, everyone would have expected New Hampshire to be considered a swing state; it’s almost always in that status, unless we’re looking at a landslide in either direction.  North Carolina would have been more of a surprise, albeit a mild one.  Obama only won the state by 14,000 votes, but the decision to hold the Democratic Convention in Charlotte was supposed to express confidence in the party’s ability to hold the state.  Instead, it’s turning into a debacle, thanks to funding issues as well as an ugly sexual-harassment scandal at the highest levels of the state Democratic Party.

Few would have guessed that Michigan was in danger of slipping away from Obama.  It’s probably the one state where Obama’s extension of the auto-industry bailout into a political-engineered bankruptcy that shafted the investors remains at all popular, but it’s apparently not popular enough.  Bear in mind that this is a poll of registered voters, not likely voters, which should tilt a little more in Obama’s favor.  And Obama’s not the only Democratic incumbent that can’t get to 50% in what had been a solidly Democratic and union state — Debbie Stabenow leads Pete Hoekstra for the Senate race, but only 46/35.

The D/R/I in the Michigan poll is 32/25/43 without leaners, and 46/37/17 when adding leaners.  In 2008, the D/R/I was 41/29/29, and CNN doesn’t have an exit poll for Michigan in the 2010 midterms, which seems odd as there was a gubernatorial election that year, which Republicans won.  The splits in this poll don’t appear to be far off from the 2008 model, but Republicans gained a lot of ground in that 2010 midterm.  I doubt we will see the same kind of turnout model in 2012 as we did in 2008.

If Michigan is really a swing state in which an incumbent Democratic President can’t get to 50% or outside the margin of error in June across a wide variety of polls, then Obama really is in serious trouble.