Mitt Romney might seem like the eventual nominee, but Rick Santorum could have some leverage by the time the party's convention rolls around in August.
How does "running mate" sound?
It is unlikely, but if he's able to stay competitive for the next three months of voting, Santorum could be in a position to make a deal with Romney to join forces on the ticket, even though the two men have been beating one another up since last month.
Santorum's strong showing in Ohio on Super Tuesday is likely to give a jolt to the conservative candidate's campaign. In his victory speech Tuesday night, after winning more primaries than most people expected him to, Santorum pledged to campaign across the country.
On paper, the race for the GOP nomination looks like a no contest. Romney has a huge lead with 401 delegates, while Santorum has 177. Newt Gingrich has 106 delegates and Ron Paul has 45. Romney's lead isn't insurmountable, but it would take something close to divine intervention to lift Santorum over him.
The first candidate to get to 1,144 wins.
The next primaries are the South, where Santorum so far has thrived. Kansas, which votes in a caucus on Saturday, will award 40 delegates; Alabama and Mississippi vote on Tuesday and will dole out 90 delegates; and Missouri's caucus on March 17 comes with another 52 delegates.
But even if Santorum were to win every single delegate in those states, which is virtually impossible anyway because they award them based on the vote percentage a candidate gets, he'd still find himself behind Romney.
Santorum is likely to get a momentum boost and some friendly media coverage should he win the southern contests, but as long as Romney wins delegates in those states as well, the numbers won't change much.
Then comes Romney's chance to return the kick, and he's likely to have little standing in his way. Big states that start voting in April will award their delegates in a "winner-take-all" fashion, meaning that unlike the southern states, in which the candidates each add to their delegate totals, only one candidate will win them all in each state after March.
The first key primary for Romney will be on March 20, in Illinois, a state where he is favored and where 69 delegates are at stake. Illinois awards its delegates proportionally, but it probably won't be a chance for Santorum to close the gap with Romney.
Starting on April 3, with Maryland and Washington, D.C., Romney will be poised to scoop up hordes of delegates in winner-take-all contests. By the time April is over, the candidates will have faced off in a handful of big East Coast states where Romney is popular: New York (95 delegates), Connecticut (28), Rhode Island (19), and Delaware (17).
Santorum will have a chance to pick up winner-take-all delegates, too, like Pennsylvania's 72, and possibly West Virginia's 31.
The two biggest contests are California, which has 172 delegates and where Romney has led in polls, and Texas, which has 155 and where Santorum has topped the polls. Those votes are months away, though, and standings are sure to shift by then.
The truth remains that Romney can afford to lose to Santorum or Gingrich in a bunch of primaries and still collect enough delegates to become the nominee.
"He has a much bigger lead than I think he's getting credit for right now," Dan Judy, a Republican strategist, said of Romney.
Romney's campaign said shortly after it squeaked by in a narrow Super Tuesday win in Ohio that "the nomination is an impossibility" for Santorum or Gingrich. A Romney campaign strategist told reporters in Boston on Wednesday that Romney needs just 48 percent of the delegates left to secure the nomination.
"We've won 53 percent of them so far," the official said. "For Rick Santorum to get to the nomination he'd have to win 65 percent of the remaining delegates, and he's only won 22 percent of them so far."
Still, the focus on the intricate delegate counting underscores a shift the Romney campaign has taken since Santorum's surprise victories. Whereas once Romney was seen as the only practical candidate for the nomination, his campaign has had to work out a delegate calculus vaguely reminiscent of the long-fought primary between Barack Obama and Hillary Clinton in 2008.
Republican observers aren't quick to see too many parallels between the two contests, though, mainly because Santorum trails Romney by a much larger gap than Clinton lagged behind Obama.
But some conservatives, including Sarah Palin, have voiced hope that the nomination isn't determined until the party's August convention.
If the race still hasn't been decided by then, it's possible that Santorum could broker a deal that once might have been thought unimaginable: forfeiting his delegates to Romney in exchange for a spot on the bottom of the ticket.
Henry Barbour, a GOP strategist who backs Romney and who is the nephew of Republican power broker Haley Barbour, has said that Santorum should be considered on the short list. Santoru has ranked relatively high in surveys of Republicans' picks for VP, though he falls behind tea party hero Marco Rubio.
The political "Intrade" prediction market says Santorum has a 6.5 percent chance of becoming the nominee for vice president.
Mark McKinnon, the media message man who worked for the campaigns of George W. Bush and John McCain, said there's "no way" Romney would pick Santorum as a running mate. "That would absolutely ensure defeat in November," McKinnon said in an email.
Warren Tompkins, a Romney supporter who has worked on a half-dozen presidential campaigns including George W. Bush's, questioned whether Santorum would be a good choice given his notoriety as a senator who lost his reelection bid badly in Pennsylvania, a key swing state.
"What good is it to have him on the ticket? Tomkins said, suggesting that another running mate could help Romney shore up support among evangelicals or social conservatives. "You can get someone who can benefit the ticket by doing that – plus bring something else to the table like winning their home state."