Rick Santorum has cruised to victory in the Louisiana Republican presidential primary but still trails Mitt Romney by a wide margin in the national delegate count for the party nomination.
Mr Romney, a former Massachusetts governor, was projected to finish second. Former House of Representatives Speaker Newt Gingrich was third, but immediately rejected suggestions he should drop out. Texas congressman Ron Paul came fourth.
Mr Santorum had strong support in all income groups except for the very wealthy, and solid backing from conservative and religious voters in the Deep South state.
"The people of Louisiana sent a loud and clear message - this race is far from over," Mr Santorum said in Green Bay, Wisconsin, where he watched the election results after making a series of campaign stops.
Mr Santorum, a socially conservative former US senator from Pennsylvania, has done well in the Deep South, winning Mississippi and Alabama earlier this month. In all, Mr Santorum has won seven state contests in March.
Saturday's primary allocated only 20 of Louisiana's 46 total Republican delegates as candidates spar for the right to take on Democratic President Barack Obama in the November general election. The rest of the delegates will be allocated at the state party convention in June.
A Republican candidate needs 1,144 delegates to secure the party's nomination. CNN's current delegate count puts Romney well ahead, with 563 delegates to Santorum's 259.
Battle moves onto Wisconsin
The next showdown in the Republican nominating contest will be in Wisconsin on 3 April. Maryland and the District of Columbia also vote that day.
Mr Santorum has pledged to stay in the race until the party's convention in August, and is likely to take heart from results in March, a month when he has won seven state contests despite failing to chip away at Mr Romney's delegate lead.
For Mr Romney, Louisiana's results suggest that he continues to struggle with the most conservative element of the Republican Party, some of whom distrust his Mormon religion and history of changing positions on social issues.
