The last 48 hours have not been kind to former Pennsylvania senator Rick Santorum’s presidential prospects.

He lost the Illinois primary badly to Mitt Romney on Tuesday and, in the process, fell 300 delegates behind the former Massachusetts governor. And, adding insult to injury, former Florida governor Jeb Bush finally decided to wade into the presidential race on behalf of Romney on Wednesday, a signal to the Republican political world that primary race is at an end.

The Romney campaign is also beginning to make the case more publicly that now is the time for Santorum to step aside. Erik Fehrnstrom, a Romney spokesman, noted that the former Massachusetts governor dropped out of the 2008 race in favor of Arizona Sen. John McCainbecause he thought it was good for the country.”

And Romney supporter Bob Dole was quoted on Wednesday night comparing Santorum’s position now to his own in the 1988 presidential primary; “I should have gotten out, but I just kept going out there,” Dole told the Associated Press’ Dave Espo.

For his part, Santorum seems set to continue on in the race. But focusing on whether Santorum should stay in the race sort of misses the point. The more important question — as it relates to Romney’s chances in the general election and Santorum’s political future — is how the former Pennsylvania senator will choose to play out what looks to be the end game of his presidential bid.

“If Santorum runs a principled campaign and then concedes graciously then he has a big future ahead,” said Steve Schmidt, who managed McCain’s 2008 presidential campaign. “If he runs a character campaign attacking Romney, then Santorum’s future is more limited.”

Think back to the 2008 Republican race. After Romney dropped out, the nomination was McCain’s. But former Arkansas governor Mike Huckabee remained in the race for weeks after that — campaigning and winning in a series of Southern states.

What Huckabee didn’t do, however, was attack McCain in any sustained way. Huckabee used his final few weeks in the race to polish his brand and make sure those who were loyal to him felt like he was giving it his all. As a result, the McCain folks didn’t push Huckabee too hard to step aside.

And, after the race ended, Huckabee turned into one of the hottest commodities in conservative circles — as a radio and television show host as well as a oft-mentioned 2012 candidate. (Huckabee announced he would not run in May 2011 on — what else? — his TV show.)

Santorum could follow a similar path, according to conversations with a number of GOP strategists, both those aligned with Romney and those not.

View Photo Gallery: Will Rick Santorum stay in the GOP presidential race until the Republican National Convention in August?

“I’d argue Santorum should start winding it down,” said Henry Barbour, a Mississippi Republican National Committeeman and Romney supporter. “That would preserve the most options for him — serving in a Romney presidency officially or unofficially or possibly running again one day.”

Barbour — along with most other Republican operatives — seem content to give Santorum at least until Wisconsin’s primary on April 3 to prove that a path, albeit narrow, still exists for him. “Santorum has done a great job of making first downs on fourth and seventeen plays,” said Schmidt. “His next fourth down play is in Wisconsin.”

Ari Fleischer, a former Bush White House press secretary, said Santorum has even more time than that. “Given how many states he has won, combined with conservative unease with former Governor Romney, I think Santorum can stay in through Pennsylvania without causing himself any harm,” said Fleischer. “If after Pennsylvania he has no chance, that’s probably the right time for him to reassess his candidacy.” (Pennsylvania will hold its primary on April 24.)

Early returns aren’t promising for those hoping for a peaceful wind down of the Santorum campaign — either now or in a month’s time.

The former Pennsylvania senator has seized on the “Etch-a-Sketch” comment made by a Romney aide on Wednesday. Not only did Santorum buy a bunch of the children’s toy at a Toys R Us in Louisiana but he’s also added an Etch-a-Sketch line into his stump speech. “You’re not looking for someone who is the Etch-A-Sketch candidate,” said Santorum on Wednesday. “You are looking for someone who writes what they believe in in stone and stays true to what they say.”

It remains to be seen whether Santorum will continue down that rhetorical road after Louisiana’s primary vote, which he is expected to win, on Saturday.

If he does, watch for more major establishment figures to come forward to both support Romney and carry a more overt warning to Santorum about what his continuing on his current course could mean to his political future.

Whether Santorum listens or not depends on what he wants. In 2016, Santorum would only be 58 years old (and only 62 in 2020) and, given how much he has overperformed expectations in this presidential race, he would almost certainly have a constituency on which to build a bid. (Of course, the potential 2016/2020 field is packed with talent on the Republican side and Santorum would not likely be in the first tier of candidates.)

On the other hand, if Santorum genuinely believes nominating Romney would send the Republican party not only to defeat in 2012 but to a place that it shouldn’t go ideologically, he may well stay in until he feels more comfortable with where the GOP is headed. And, Santorum knows that he is currently one of the last two men standing in this race — a prime spot that he may never be able to replicate in future races.

Remember: It’s not when Santorum decides to begin winding down his campaign that matters. It’s how he does it.

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