Rick Santorum and his wife Karen greet supporters as they walk through Old San Juan, Puerto Rico, March 15, 2012. (AP)

Another week and another chance for Rick Santorum to change the dynamics of the Republican presidential race.  A Santorum victory in Illinois would raise fresh doubts about what Mitt Romney argues is his unstoppable march to the nomination.

Romney says it is all about the math and that it is simply not possible for either Santorum or Newt Gingrich to win enough delegates in the remaining primaries and caucuses to win the nomination.

But what they can do, and what Santorum freely admits he is trying to do, is prevent Romney from securing the 1144 delegates he needs at the Republican convention in August and make the Tampa conclave a true contested convention, the first one in the Republican Party since incumbent President Gerald Ford narrowly defeated Ronald Reagan in 1976.

At the moment, a simple reading of the math clearly favors Romney and suggests that his wrapping up the Republican race is more a question of when, rather than if.  In the wake of his victory in Puerto Rico on Sunday, the Associated Press unofficial delegate count gives Romney 521 compared to 253 for Santorum, 136 for Gingrich and 50 for Ron Paul.

Santorum’s problem is there are very few winner-take-all contests remaining in the Republican slate of primaries and that means even when he wins a state he will share some delegates with Romney.  It’s just not possible for Santorum to win the large chunks of delegates he needs to make a dent in Romney’s delegate lead and change the complexion of the race.

Rick Santorum signs autographs after speaking at a campaign rally, March 19, 2012, in Dixon, Illinois. (AP)

What Santorum is hoping for is to demonstrate that he and not Romney has the political momentum.  Santorum can’t win the math argument so he has to pull an upset and stop Romney in a state where he is favored, like Illinois, in hopes of changing the argument away from the delegate count to who has the momentum heading into the rest of the primaries.  A win in Illinois would give Santorum a chance to make that argument, but the polls show he’s trailing and he could come up short as he did in two other crucial Midwest tests—Michigan and Ohio.

Gingrich and Paul Not Going Away

A lot of experts thought Newt Gingrich might end his presidential quest last week after disappointing finishes in both Alabama and Mississippi.  But Gingrich is soldiering on and now targets the March 24^th contest in Louisiana as perhaps his last chance for a breakthrough in order to remain in the race.

The Gingrich strategy always assumed he would build on a base in the South, starting with his victory in South Carolina in January and another win in his former home state of Georgia on Super Tuesday (March 6).  But the Gingrich magic never translated across borders into other southern states and that effectively stalled his strategy and allowed Rick Santorum to become the darling of conservative activists suspicious of Mitt Romney’s commitment to the conservative cause.

Newt Gingrich speaks at the airport in Lake in the Hills, Illinois, March 15, 2012. (AP)

The question is, will Gingrich decide it’s time to get out of the race if he loses in Louisiana on Saturday or will he stick to his pledge that he’s in the race until the convention?  At this point probably only Gingrich knows for sure.

Then there is Ron Paul, who keeps on despite having less and less impact each week.  Paul wants to bring a stash of delegates with him to the convention in Tampa in August so at the very least he can claim a speaking spot.  But his low total so far, which the Associated Press estimates at 50, may not buy him one of the coveted prime time TV address slots during the four nights of the convention.

On the other hand, the eventual nominee — be it Romney, Santorum or someone else not yet picked up on radar — is not going to want to go into the general election campaign for November having alienated Paul’s diehard supporters.  Not only that, they also know that any perceived insult or slight of the Paul crowd might just convince the congressman to change his mind and run as a third party presidential candidate anyway, further complicating a difficult Republican challenge of the president in November.