US presidential hopeful Rick Santorum has swept the contests for the Republican Party nomination in Minnesota, Missouri, and Colorado
Mr Santorum outperformed longtime front-runner Mitt Romney, who has struggled to connect with the party's conservative base.
Supporters in Missouri heard Mr Santorum declare victory for all those "building the conservative movement".
The eventual nominee will face Barack Obama in November's election.
Former House of Representatives Speaker Newt Gingrich hardly campaigned in the three states that voted on Tuesday, and did not even appear on Missouri's ballot.
Distrust of Romney
In Minnesota's caucuses, with 95% of the vote counted, Mr Santorum was on 45%, while Texas Congressman Ron Paul was on 27% and former Massachusetts Governor Romney had 17%.
In Missouri's primary, with all votes counted, Mr Santorum won with 55%, well ahead of Mr Romney at 25% and Mr Paul on 12%.
After an anxious wait, the Republican Party chairman in Colorado eventually declared Mr Santorum the winner in that state's caucuses, too.
Final results showed Mr Santorum won the state with 40% of votes, with Mr Romney on nearly 35%.
Pitching himself as the only true conservative in the race, Mr Santorum had campaigned hard in Minnesota and Missouri - states with significant blocs of Tea Party and evangelical Christian voters respectively.
Polls had showed him performing well, and predicted the possibility he would win in either or both states. But while Mr Romney's team had sought to manage expectations, they still retained hopes of a Colorado victory.
"Conservatism is alive and well in Missouri and Minnesota," he said before the Colorado results were known.
"I don't stand here to be the conservative alternative to Mitt Romney. I stand here to be the conservative alternative to Barack Obama."
The former Pennsylvania senator, who had not won a contest since his narrow win in Iowa's caucuses in January, had been