Santorum sweeps Kansas Republican caucuses
The conservative former senator from Pennsylvania was well ahead of former Massachusetts Gov. Mitt Romney, who was at 21 percent, and former Speaker of the House Newt Gingrich at 14 percent.
Texas Rep. Ron Paul had 12 percent.
Santorum now has some bragging rights before the more contested races next week in Alabama and Mississippi, where victories could solidify his status as the conservative alternative to front-runner Romney.
The value for Santorum of winning Kansas "is in not dropping the ball," said Ruy Teixeira, political analyst at the liberal Center for American Progress.
The Republican race to be the nominee to face President Barack Obama in November's general election could come down to a two-man fight between Santorum and Romney.
Victories in Alabama and Mississippi for Santorum could knock out Gingrich, who is fighting to stay in the race and will face increased calls to drop out if he fails to make a mark in those Southern primaries. Gingrich's home state is Georgia.
A staunch opponent of abortion and gay rights, Santorum's conservative message was welcomed in the Midwestern state of Kansas where he campaigned more than any other candidate.
"I don't want to vote for Romney, he's almost like a Democrat. I'd vote for Newt, but too much baggage behind it. I'd vote for Ron Paul, but a nuclear Iran is not an option. I gravitated toward Santorum. ... He's the only one that's consistent," said voter Shane Williams, 49, in Topeka.
Santorum will take more than 20 of the 40 delegates up for grabs in Kansas, CNN said.
Romney described Tuesday's Southern primaries as an "away game" for him and has been concentrating on a longer-term search for delegates.
Taking the fight for the White House far into the Pacific Ocean, Romney quietly picked up more delegates over the weekend. He won all nine delegates in the U.S. territory of Guam and nine in the U.S. commonwealth of the Northern Mariana Islands, nearly 8,000 miles (13,000 km) from Washington.
Candidates need to win 1,144 delegates to clinch the presidential nomination at the party's national convention in Tampa, Florida, in August. Romney is well ahead with more than 400.
He was also harvesting delegates in Wyoming on Saturday, where he won five of the 12 at stake. Three delegates were still to be determined there.