Washington: In a major setback for frontrunner Republican presidential hopeful Mitt Romney, former senator Rick Santorum scored twin victories in Alabama and Mississippi primaries to turn the nominating fight into a two-man race.

Santorum's victory over former Massachusetts governor Romney, who earlier in the day said his closest rival's campaign was reaching a "desperate end", also came as a blow to former House speaker Newt Gingrich, who finished second in both states.

With over 96 percent votes counted, Santorum led with 35 percent in Alabama, followed by Gingrich at 30 percent, Romney at 28 percent and House member Ron Paul at 5 percent.

In Mississippi, Santorum had 33 percent. Newt Gingrich was at 31 percent, Romney at 30 percent and Ron Paul at 4 percent.

"We did it again," Santorum told supporters on Tuesday night in Lafayette, Louisiana, which holds its primaries March 24.

The state's Indian American governor Bobby Jindal is yet to endorse any of the four remaining candidates vying for the right to challenge President Barack Obama in November.

Santorum, whose Alabama and Mississippi victories give him 10 wins to Romney's 16, poked at the front-runner as he reiterated his stance that he is the viable conservative alternative to Romney.

Gingrich, who has won contests in South Carolina and Georgia, which he represented in Congress for two decades, noted that he walked away with nearly as many delegates as the others and pledged to take his candidacy to the Republican convention in Florida in late August.

Romney was hoping for a victory in a region dominated by social conservatives, who have been hesitant to support his candidacy.

His advisers said that he was still in the strongest position to win the party's nomination and would continue ahead with his state-by-state strategy to win delegates.

Forty-seven delegates are up for grabs in Alabama, with 37 at stake in Mississippi, all being divided proportionally. Seventeen delegates are to be allocated in Hawaii and nine in American Samoa.

Romney's campaign has been holding up its large lead in delegates as a reason for Gingrich and Santorum to get out of the race.

Romney still is far short of the 1,144 delegates needed to clinch the nomination-he holds a 459-203 lead over Santorum, with Gingrich at 118 and Paul at 66, according to an estimate.

(Agencies)