The calendar, too, is a problem for Santorum, his objections aside.
In a memo released March 11, his campaign said Romney's claims of delegate superiority were based on "fuzzy math. ... Simply put, time is on our side."
In the days since, Romney has won 109 delegates, Santorum 44.
In The Associated Press count, Romney has 563 of the 1,144 delegates needed to clinch the nomination at the convention in Tampa, Fla., next summer. Santorum has 263, Gingrich 135 and Paul 50. That gives the front-runner more than half, a pace that will let him seal his victory by the time the primaries end on June 26.
Past performance is no guarantee of future results, and Santorum has every reason to anticipate victory on Saturday in Louisiana and elsewhere.
Yet the mid-range forecast is less than sunny for him.
He is not on the ballot in Washington D.C., effectively conceding 16 delegates in one of three primaries on April 3. Restore Our Future is already advertising on television in Maryland, the second of that night's three contests.
Wisconsin, the third, is likely to be the next big showdown. Restore Our Future has already sunk $2.3 million into TV advertising in the state, getting the sort of head start that helped Romney come from behind in Michigan and Ohio, and prevail in Illinois. Santorum has so far spent about $50,000.
Then comes a three-week break, followed by primaries in Connecticut, Delaware, New York, Rhode Island and Santorum's home state of Pennsylvania. If Romney and Restore Our Future challenge him there in Pennsylvania, he will be stretched to mount much of a campaign in the other states.
"Saddle up," Santorum exhorted his supporters on Tuesday night after losing Illinois. He spoke not far from the historic battlefield at Gettysburg, Pa., where the tide turned decisively toward the better-equipped and financed Union in the Civil War.
"We're almost there," said Romney.
EDITOR'S NOTE — David Espo covers politics for The Associated Press.
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