Today, Republicans in Wisconsin, Maryland, and Washington D.C. will go to the polls to vote for one of the four remaining Republican presidential candidates. In what will likely turn into a showdown between Mitt Romney and Rick Santorum, Wisconsin is at the center of today's political discourse, with 42 delegates up for grabs in the winner-takes-all primary.

The Wall Street Journal and CNN have both been tracking the primaries and estimate that Romney has somewhere between 568 and 571 delegates, to Santorum's 264-273 delegates. Gingrich and Paul trail with around 135 and 60 delegates, respectively. And while Romney's three opponents cannot mathematically surpass him in delegates, they can block him from getting the nomination before the Tampa convention, as illustrated in Chris Weyant's political cartoon for The Hill above.

What's at Stake? 

With the endorsement of Wisconsin's Republican Senator Ron Johnson and accompanied by Conservative Paul Ryan, Mitt Romney has been campaigning heavily in Wisconsin, because a win for Romney could decisively bring him passed the halfway mark in terms of delegates. Outspending Santorum 4 to 1, Romney leads in the most recent RealClearPolitics poll, ahead of his rivals by 7.5 percentage points. With Republican leaders now urging the party to rally around Romney, a win in Wisconsin could be the push he needs to convince Republican voters of his electability against President Obama.

Speaking to the importance of Wisconsin in this race, Republican National Committee Chairman Reince Priebus says:

"I think that because Wisconsin has been at the political epicenter of this country and represents some of the same arguments that are relevant in every corner of this country, whoever wins this Wisconsin primary is going to have some very serious bragging rights."

A win for Santorum, however, could be more significant as he struggles to convince the Republican Party that the race is not over. A win for the former Pennsylvania Senator could reignite the headlines that Romney is having a hard time locking up the nomination, revealing his weaknesses as a candidate. Political analysts agree that a win for Santorum is necessary for him to stay in the race.

Where are Newt Gingrich and Ron Paul? 

Running low on campaign funds, Newt Gingrich has been somewhat absent from the race. In a recent campaign move, he began to charge supporters $50 to pose in a picture with him, a clear indication that his campaign is in trouble. While a Gingrich spokesperson defended the move, citing that "some campaigns make you travel all the way to Wall Street to pay $2,500 for a photo with a candidate," there's no denying that his campaign is on the brink of collapse. Skipping today's primary in Wisconsin, Gingrich's campaign hopes that a win in Delaware on April 24th would once again bring national attention on the candidate, returning relevancy to his campaign.

In an attempt to spread his message across the nation, Ron Paul has been focusing on a different crowd, and will spend today speaking at some of the most liberal college campuses in California. Speaking of the cost of war in Afghanistan and Iraq, and the dangers of rising tuition for students, Ron Paul attracts large crowds of enthusiastic supporters, and while he has yet to win a caucus or primary, he has been making an impact on the nation's youth. Since September of 2011, the Paul campaign has launched 591 "Youth for Ron Paul" chapters, 60 of them in California, a factor that may come in play come June 5th.