Rick Santorum scored what his campaign trumpeted as a "landslide" victory in Kansas's Republican presidential primary on Saturday, and he's expected to do well in Tuesday's Deep South contests in Mississippi and Alabama.

But while Santorum bested Mitt Romney by more than 30 points in Kansas, the fight for the Republican nomination is not about winning the popular vote. From here on out, it's all about delegate math—and Romney continues to maintain a major edge over his rivals.

While Santorum won 33 of Kansas's 40 delegates at stake on Saturday, Romney kept pace. He racked up 32 delegates from low-key contests in Wyoming and in the territories of Guam, the Northern Mariana Islands and the Virgin Islands. And despite his poor showing in the state, Romney scored 7 delegates out of Kansas. All told, the former Massachusetts governor ended the weekend with 39 new delegates, compared to Santorum's 36.

On Tuesday, 116 delegates are up for grabs—including 49 in Alabama, 38 in Mississippi, 20 in Hawaii and 9 in American Samoa. But none of the states are "winner take all"—which means there is little opportunity for Santorum or Gingrich to make big gains on Romney as long as the front-runner finishes a close second or third place.

According to a tally by the Associated Press, Romney currently has more than twice as many delegates as Santorum—454 vs. 217. Newt Gingrich has just 107 delegates, while Ron Paul has 47 delegates. To win the nomination, a candidate has to win 1,144 delegates.

Last week, a Romney campaign adviser argued that it would take "an act of God" for Santorum or Gingrich to match the former Massachusetts governor in the race for delegates. By their calculation, Romney needs to win 48 percent of the remaining delegates in the race to win the nomination, whereas Santorum would have to win 65 percent of delegates and Newt Gingrich 70 percent.

In a campaign stop Sunday, Santorum dismissed that talk—insisting he still has a viable shot to best Romney for the nomination.

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"You have Gov. Romney now saying, 'Oh this race is over that mathematically it can't work," Santorum declared, per NBC News. "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. This isn't about math. This is about vision, it's about leadership."

Meanwhile, Santorum strategist John Patrick Yob pushed back against Romney's stats in a memo leaked to reporters, calling Romney's delegate projections "fuzzy math" and a "defensive smokescreen" to distract from Romney's inability to win key constituences in the South and beyond.

"The situation is only going to get worse for them and better for Rick Santorum as time passes," Yob wrote. "Simply put, time is on our side."

But is it?

As the Romney campaign noted in its briefing with reporters last week, there are only four statewide "winner take all" contests coming up that give Santorum or Gingrich a significant chance to catch up to Romney in the delegate race. Yet all are in places that are friendly to Romney, including Utah (40 delegates), Delaware (17 delegates), New Jersey (50 delegates) and Washington, D.C. (17 delegates)—and Santorum did not qualify for the ballot in the nation's capital.

In its memo, the Santorum campaign claimed Wisconsin—with 42 delegates—and Maryland—with 37 delegates—are winner-take-all states, but Davidson College's Josh Putnam, who tracks the delegate race on his blog, Frontloading HQ, says those states are winner-take-all by congressional district—which still allows each of the candidates to amass delegates around the state.

Still, the Santorum campaign insists it can make up ground by winning the majority of delegates in states like Missouri (52 delegates), Santorum's home state of Pennsylvania (71 delegates), and Louisiana (46 delegates). His campaign argues that wins in Missouri and Louisiana could translate into momentum heading into other key primaries and help him rack up more delegates than Romney.

Both campaigns are putting a heavy emphasis on the Illinois primary March 20. In its briefing last week, the Romney campaign argued it has a stronger organization and a more comprehensive slate of well-known delegates in the state. (Unlike other states, Illinois lists its delegates on the ballot identifying them as surrogates for particular candidates). The Santorum campaign, Romney aides noted, failed to qualify for the ballot in four of the state's 18 congressional districts.

But not unlike Florida, Michigan and Ohio, Romney faces an uphill battle when wooing rural voters in the state. A WGN-TV/Chicago Tribune poll released Sunday found Romney and Santorum statistically tied in the state—35 percent for Romney to 31 percent for Santorum, with a margin of error of plus or minus 4 percentage points. Romney leads in the Chicago area, and Santorum's strength is downstate, where voters tend to be more conservative.

Romney hoped to lock up the Republican presidential nomination in Illinois, in part because of the image of winning in President Obama's backyard. But as Slate's John Dickerson notes, the Santorum campaign is plotting methods to keep his campaign alive well into the party's convention in Tampa, in part by trying to pick off delegates from Gingrich or even wavering Romney supporters. Meanwhile, the Romney campaign is planning similar efforts, targeting delegates at state conventions in Iowa and other states.

"I think you'll see at the end of the day that Rick Santorum will lose delegates," a Romney strategist told reporters last week.

In other words, the long slog is just beginning.

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