(Image Credit: Ross D. Franklin/AP Photo)

The long slog that the Republican presidential primary has become will swing through the Deep South Tuesday when voters in Alabama and Mississippi head to the polls, but a decisive result of any kind seems unlikely to say the least.

For frontrunner Mitt Romney, who appears all but certain to secure the nomination eventually, a victory in either state would be a massive boost, giving him a sorely needed southern success. For Rick Santorum, a win would bolster his argument that the race is far from over. And Newt Gingrich may need victories in Alabama and Mississippi more than either of his rivals, but his campaign has walked back comments that both states are must-wins.

A series of primaries over the weekend provided a preview of the race to come. Santorum romped to a commanding win in Kansas, the weekend's single biggest prize, but Romney captured the bulk of delegates in Guam, the Northern Marianas and the Virgin Islands, giving the former Massachusetts governor more delegates from the four contests than Santorum.

The race, it seems, has become a battle of math versus momentum . Even if Santorum manages to put together a winning streak in the upcoming states, Romney, with his superior campaign organization, will likely to continue to amass so many delegates that the nomination will ultimately be his.

The math argument is one that the Romney campaign has been making since Super Tuesday.

"The nomination is an impossibility for Rick Santorum or Newt Gingrich," a Romney campaign strategist said last Wednesday, claiming that it would take " an act of God " for one of their two rivals to win.

If Romney has cold, hard math on his side - to date Romney has secured 454 delegates, more than double the 217 that Santorum has - then Santorum has momentum on his. The former Pennsylvania senator leads Romney 34 percent to 30 percent in a new national CBS/New York Times poll and he stands to do well in a series of upcoming states, including Alabama and Mississippi, where even Romney aides acknowledge that their candidate may not have that much support, despite the endorsement of the governors of both states and, for good measure, comic Jeff Foxworthy.

"When we have our nominee going out there and trying to sell the American public to vote for him because of mathematics, we are in very, very tough shape," Santorum said at a campaign stop over the weekend. "This isn't about math. This is about vision. It's about leadership. It's about taking this country in a direction that is critical because big things are at stake in this country."

For Santorum to keep making his momentum argument, success in Alabama and Mississippi is imperative. Recent polls show a close race in both states. What Santorum must have worried is that it is entirely possible for him to win both states but still come out as the loser on the day in terms of delegates. Both Alabama and Mississippi award delegates proportionally, so Romney is likely to do well enough to gain at least some delegates there. In addition, caucuses will also be held in Hawaii and American Samoa, where - as evidenced by his success in Guam, the Northern Marianas, and the Virgin Islands - Romney is considered likely to win.

Gingrich, meanwhile, lags far behind both Romney and Santorum, making the contests in Alabama and Mississippi potentially more important for him than for his rivals. The former House speaker has only won two states - South Carolina and Georgia - and a total of 109 delegates to date. Last Wednesday, when asked if Gingrich had to win both Alabama and Mississippi to remain a credible candidate in the race, his campaign spokesman R. C. Hammond replied, "Yes."

Gingrich has been walking back those comments ever since. In an interview with The Associated Press last week, Gingrich vowed to stay in the race until the GOP convention in Tampa, Fla., in August, even if he loses both southern states Tuesday.

"We'll clearly do well enough to move on and I think there's a fair chance we'll win," he said. "But I just want to set this to rest once and for all - we're going to Tampa."

While Gingrich's continued presence in the race might seem irrelevant, it could affect the fate of the nomination by siphoning votes from Santorum , his rival for the conservative alternative to Romney. Santorum, for instance, might have won states such as Ohio, Georgia and Alaska if Gingrich had not been on the ballot.

Both Gingrich and Santorum seem inclined to keep fighting in the coming months, even if they are almost certain to lose the nomination to Romney. According to a new ABC News/Washington Post poll released Monday, 74 percent of Republicans and Republican-leaning independents expect Romney to be the nominee. However, only 31 percent want to see him win the nomination.

Although they trust Romney more than his rivals to improve the country's economic situation, Republicans and Republican-leaning independents favor Santorum to handle social issues and they are deadlocked between the two candidates on who best reflects the core values of the party.

Win or lose on Tuesday, Romney clearly still has some work to do to change an ambivalent, resigned electorate into an inspired one this fall. When voters in Alabama and Mississippi head to the polls Tuesday, a day after Romney's 65th birthday, he will be hoping for a belated, but welcome, birthday present.

"This could be an election that comes down to a very small margin between the three people running here most aggressively, and if you will give me your support, that would not only give me more delegates - by the way, we're about two and half times ahead in the delegate race, so we're doing really well, but I need even more delegates - so if you guys are able to do that for me, we can, well, take this over, over the top at a very fast pace," Romney said today at a campaign stop in Mobile.

But the chance of a result on Tuesday good enough to knock out his two key opponents once and for all appears slim. The slog, it seems, will go on and on…

Matthew Jaffe is covering the 2012 campaign for ABC News and Univision.