His mathematical chances of winning the GOP nomination are slim. He came up short in the crucial races of Michigan and Ohio. And he just lost the GOP primary contests in DC, Maryland, and Wisconsin.
But Rick Santorum -- despite starting out this presidential season as an afterthought -- has already accomplished a few important feats that shouldn't be overlooked as attention begins turning to the general election. First, with limited campaign funds and almost no real infrastructure, he ultimately emerged as Mitt Romney's chief rival.
Jae C. Hong / AP
Republican presidential candidate Rick Santorum sits in a booth at Bob's Diner in Carnegie, Pa.
In fact, Santorum's actually won more states so far than Mike Huckabee did in 2008, 11-8. And he's won as many contests as Romney did four years ago.
Second, even if he doesn't win another primary race, Santorum could be a significant player in the 2016 or 2020 presidential contests, although he would face plenty of serious competition (from the likes of Marco Rubio, Chris Christie, Bob McDonnell, etc.).
And third, and perhaps most importantly, Santorum has repaired some of the political damage he sustained in 2006, when he lost his Senate re-election bid in Pennsylvania by a whopping 18 percentage points, 59%-41%.
"It's hard to argue Sen. Santorum hasn't significantly raised his profile nationally among Republican voters, donors and members of the media due to his primary campaign performance," GOP strategist Danny Diaz tells First Read.
Of course, it's exactly that repaired political image, Republican political observers say, that could be at stake in the April 24 primary in his home state of Pennsylvania. A win there could justify him staying in the presidential contest -- and could serve as a springboard to the May primary races.
But a loss in his home state could be embarrassing. A recent Quinnipiac University poll, conducted before Tuesday's primaries, showed Santorum leading Romney by only six points in the state, 41%-35%.
As GOP political consultant Mike Murphy, who once worked for Romney, tweeted, "Will [Santorum] figure out this week that his potential '16 hand is now stronger than his '12 hand and fold? Or stay in and ruin his long game?"
And if he decides to stay in the race, how he campaigns could be just as important to his reputation, Republicans argue.
"The story until now is a pretty compelling one about a leader who rose from also-ran status to one-time front-runner. If he gets out now, or stays in but runs a positive-only campaign, that narrative will remain largely intact," says GOP political adviser Todd Harris.
"But if he continues with a quixotic slash-and-burn campaign against the man everyone knows is going to be our nominee, he risks being remembered not as a come-from-behind leader, but as a petulant politician who put selfish self-interest ahead of defeating President Obama."