CNN, NBC, CBS and ABC all said soon after the polls closed their reading of the vote tallies led them to conclude the former U.S. senator from Pennsylvania had beaten Mitt Romney, as pre-election polls had forecast.
Despite his victory in Louisiana, which had 20 delegates at stake, political analysts say Santorum won't gain much ground on Romney, who CNN calculates has 563 delegates in his corner -- more than double Santorum's 251 -- en route to the 1,144 it will take to win the GOP nomination.
In Louisiana's closed primary, meaning only registered Republicans could vote, the delegates are allocated among candidates who receive more than 25 percent of the vote. Another 26 delegates will be allocated at a state convention in June.
Santorum gained momentum with primary wins in Alabama and Mississippi but lost to Romney in Puerto Rico and was defeated again in Illinois, where Romney had a 12-point win.
Now, said Bruce Haynes, a GOP strategist and managing partner of Purple Strategies, a bipartisan public affairs consulting firm: "Santorum can't just win; he has to win big. He's the one who needs to 'shake up' this race. Another ho-hum win in the South doesn't cut it. He's on a political bridge to nowhere and is running out of time to change destinations."