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 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 delegate count gives him an easier path to the nomination in the next few months.

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

Romney 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.

The tight three-way race on Tuesday gave Santorum no advantage at all in the scramble for delegates, according to a CNN estimate. Romney likely ended the night with a 480-234 lead over Santorum, giving him the same 246-delegate margin that CNN estimated he had before the primaries.

As far as Romney's concerned, he's going to get about a third of the delegates tonight, Republican strategist Rich Galen 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.

Though he could do well at Missouri's caucuses this weekend, Santorum is already 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.

GINGRICH FACTOR

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, referring to the number of delegates needed to win the nomination before the primary season ends in June.

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.