Time and math work against Santorum's White House bid

U.S. Republican presidential candidate Rick Santorum addresses the Alabama Republicans forum at the Alabama Theater in Birmingham, Alabama March 12, 2012.

WASHINGTON (Reuters) - Rick Santorum is winning the hearts of Republican conservatives but the cold realities of time and math are working against his presidential election effort.

Santorum effectively became the only conservative challenger to Mitt Romney left standing when he narrowly won the Alabama and Mississippi primaries on Tuesday, as good as ending Newt Gingrich's presidential ambitions.

That set up a one-on-one battle between Santorum and Romney, whose clear lead in the fight to win the 1,144 delegates needed to win the nomination gives him an easier path in the next few months.

"It's a little too late for Santorum," said Republican strategist Adam Temple.

Romney, the former Massachusetts governor, won up to 30 percent of the vote in the two Deep South states but still failed to dispel doubts that he can win over conservatives.

Numerically, that may not matter much.

Although exact numbers are hard to come by, Romney actually won more delegates than Santorum on Tuesday, according to media estimates.

The race was so tight in the South that the delegates were split almost evenly between the three hopefuls but Romney also won caucuses in Hawaii and American Samoa.

His lead over Santorum increased by 9 delegates to 255, according to CNN. Romney had 489 delegates, compared to 234 for Santorum, CNN said.

"They can keep doing this all the way until June and the delta between he and Santorum gets wider and wider and the time to catch up gets narrower and narrower," Republican strategist Rich Galen said.

ROUGH ROAD AHEAD FOR SANTORUM

Although he could do well at Missouri's caucuses this weekend, Santorum already is starting behind in next week's Illinois primary after failing to qualify for several ballots there. In the District of Columbia, another place where Santorum is not on the ballot, 19 delegates are up for grabs on April 3.

Other states voting in April such as Maryland, Connecticut, Delaware, New York and Rhode Island would seem to favor Romney.

Santorum's home state of Pennsylvania votes on April 24 but even an enormous statewide win for him there, which seems unlikely given his massive Senate loss in the state in 2006, would not give him enough delegates to really contend with Romney.

"Once the dust clears, you'll be able to look and see that there really will be no ground that our opponents have made up against Mitt Romney," Eric Fehrnstrom, a senior Romney adviser, told CNN.

"If someone can explain to me the pathway to 1,144, I'm all ears, but mathematically we're fast approaching the point where it's going to be a virtual impossibility," he said.

Gingrich's chances of becoming the Republican challenger to President Barack Obama are greatly reduced but he could stay in the race for a while, damaging Santorum by splitting the conservative vote.

"It's a two-man race but with Gingrich in, it's a two-man race with one guy fighting two wars and that's Santorum," Galen said.

Gingrich said after Tuesday's results that he was not quitting.

"He's hanging in there long enough to hurt Santorum," Temple said.

(Editing By Alistair Bell and Bill Trott)