On this week's Chris Matthews Show, Richard Stengel of Time magazine made a prediction in the "Tell me something I don't know" segment of the program:

John Edwards. Senator John Edwards--remember him?--who's been conspicuously silent since he dropped out of the race, will endorse a Democratic candidate probably before North Carolina, certainly before North Carolina, possible before Pennsylvania. And our own Mark Halpern [sic] on the page [sic] says it's going to be Senator Hillary Clinton.

The transcript needed some quote marks or capitalization, since Stengel was referring to "The Page" on the Time website, written by Mark Halperin. Now, some may take this with a grain of salt, since Halperin has already gotten in some trouble over characterizing what John Edwards is thinking. But for the sake of discussion, let's take Stengel at his word, and assume his (or Halperin's) prediction is accurate.

If John Edwards openly endorses Hillary Clinton, what could it mean to the nomination race? For starters, it would surprise a lot of Edwards supporters. Most of the unions backing Edwards have moved into the Obama camp, and they may be disappointed by Edwards going the other direction. However, one of Edwards' core constituencies of support was among white men -- who are now firmly in the Clinton camp (if exit polls are to be believed). So while either endorsement from Edwards is going to please some of his supporters and annoy some others, it's not outside the bounds of possibility that he would back Hillary, and influence voters as a result.

The problem for Edwards is that the window of opportunity to make such an endorsement (and have it be relevant) is fast closing. I have written about this before, calling on Edwards, Gore, and Richardson to make up their minds, already. And it bears mentioning that if Edwards endorses Clinton, but Gore (or, to a lesser extent, Richardson) endorses Obama, it could be seen as balancing out for the two campaigns.

But just taking Edwards' endorsement of Clinton on its own, how much would it help Hillary and how much could it hurt Obama? Because Edwards has waited so long to do so, two things are immediately apparent. The first is there aren't that many states left to vote. The second is that Edwards' endorsement may be reduced to a regional influence rather than a national one.

The only states remaining in the contest that an Edwards endorsement would probably carry any weight are the Appalachian states -- North Carolina, Kentucky, and West Virginia. John Edwards served as U.S. Senator from North Carolina, so this is where his opinion would likely matter the most. Kentucky and West Virginia share similar demographics in some ways to North Carolina, and in other ways not so much. So his influence on voters there would be less than in North Carolina, but probably more than in any of the other states left to vote (including Pennsylvania). Even in North Carolina, Edwards' influence may not be as weighty as some would think. He did, after all, quit his Senate seat when it became apparent that he might not win reelection there.

But again, for the sake of argument, let's assume that Edwards' endorsement would be listened to closer in these three states than anywhere else in the country. This could be a problem for Barack Obama. As things currently stand, Obama has a solid lead in North Carolina. Polls for Kentucky and West Virginia are almost non-existent, leaving us to pure speculation about the electorate in these two states. But while Obama has been consistently leading Clinton in North Carolina, his lead may not be insurmountable for Hillary -- with Edwards at her side.

Hillary Clinton actually led in the North Carolina polls for all of the later part of 2007 -- it wasn't until very early in 2008 that Obama started leading. His current lead is only about 7 or 8 points, so it's not inconceivable that Edwards could swing some of those votes back to Hillary's column. And maybe, just maybe, as goes North Carolina, so goes Kentucky and West Virginia. Maybe.

If that does indeed happen, it likely wouldn't be enough to let Hillary catch up in pledged delegates before the convention, so even if she won in these three states (with her expected victory in Pennsylvania), Barack Obama will likely still lead in pledged delegates when the Democratic Convention begins. But psychologically, it would be a huge victory for Clinton, and a huge defeat for Obama, for several reasons.

Obama has done exceptionally well in the South so far, winning six states (AL, GA, LA, MS, SC, VA) to Clinton's two (AR and TN). Winning three more states would even things up for Hillary, especially if she also re-wins in Florida. The other big reason this would be a big loss for Obama is bigness. If Hillary wins Pennsylvania, Michigan, and Florida -- and also North Carolina -- then she will have swept all the "big" states except Illinois, Obama's home state. This would greatly bolster her argument for how electable she is in the general election. And no matter how the remaining states vote, this argument -- made to the superdelegates -- may be what decides the nomination.

Now, there are a lot of "ifs" in all of that, I freely admit. If Edwards endorses Clinton. If she can grab North Carolina. If West Virginia and Kentucky follow. If she can successfully make the electability argument to the superdelegates. If, if, if. But it's a clearer path to her actually winning the nomination than anything else the Clinton camp has been touting of late, so even though it rests on everything breaking Clinton's way, it's at least worth examining at this point.

So, Senator Edwards... we're all waiting to hear whether Richard Stengel was right or not. How long is it going to take you to make up your mind? That creaking sound you hear is your window of opportunity, slowly sliding shut. If you're going to endorse either candidate, you need to do so soon, before it slams shut entirely.

[Happy St. Patrick's Day to all my Irish and wannabe-Irish readers! Or, more properly, in the original Gaelic: Beannachtaí na Féile Pádraig oraibh!]

Cross-posted at The Huffington Post

-- Chris Weigant