Polls show a three-way tie going into today's Deep South primaries. The results could be revealing, but the delegate calculus won't change.

Reuters

For watchers of the still-ongoing Republican primary, Tuesday's primaries in Alabama and Mississippi both do and don't matter.

Polls are showing a tight three-way race in both states. Newt Gingrich has basically bet his whole campaign on his ability to make a comeback in the South, and many appear to be responding to the onetime Georgian's vehement pitch. Rick Santorum hasn't managed to convince hard-core conservative voters that he's the only one they should rally behind if they want to topple Mitt Romney. And Romney is capitalizing on the split, along with his organizational advantages, to stay competitive, with a chance to win or come close in this unfriendly territory.

How up in the air is it? The New York Times' Nate Silver forecasts a 1-point Gingrich victory in Alabama and a Romney win by half a percentage point in Mississippi, with the caveat that polls in these states have proved unreliable in the past.

The Southern contests matter as a barometer of GOP base sentiment: Are conservatives and evangelicals coming around to Romney? They matter as a referendum on the viability of Gingrich in particular -- these two states are his last chance, and he knows it. The flip side of that, too, is a referendum on Santorum's ability to go forward: Is the base really interested in strategically coalescing behind a Romney alternative in order to deny him the nomination? Or are they just protest-voting for someone they like better?

The contests also feature a share of down-ballot intrigue. Several House incumbents in both states face primary opponents who embody the virulent strain of anti-incumbent sentiment rampant in the body politic. Though the challengers are long shots, one House incumbent, Ohio's Jean Schmidt, has already fallen unexpectedly after underestimating a challenger's appeal.

But these primaries don't matter in the sense that they're unlikely to change the standing of the primary race. Nor are they relevant to the November presidential stakes -- there's almost no way the GOP nominee doesn't win these states in the general election.

As the primary stands, Romney has a near-prohibitive edge in terms of delegates. Both Alabama and Mississippi award delegates proportionally, meaning even if Romney loses narrowly, he'll get delegates out of these contests, maintaining his edge over the competition. (Hawaii and American Samoa also hold caucuses Tuesday, and if past contests in the Pacific Islands are any guide, those votes stand to add to Romney's delegate lead.)

Thus, the essential calculus of the competition will remain unchanged by the Alabama and Mississippi primaries. But with two more states on the board, the road for Romney's opponents will be narrower than ever, and the primary nearer to its messy final conclusion.

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