Rick Santorum scores in Deep South

Presidential hopeful Rick Santorum bolsters his White House hopes with key Republican primary victories in the Deep South.

Santorum said his success in Mississippi and Alabama proved that a conservative candidate had the best chance of squaring up against President Barack Obama.

(SOUNDBITE) (English) RICK SANTORUM, REPUBLICAN PRESIDENTIAL CANDIDATE:

"We will compete everywhere, we will compete everywhere. The time is now for conservatives to pull together. The time is now to make sure, to make sure that we have the best chance to win this election, and the best chance to win this election is to nominate a conservative to go up against Barack Obama who can take him on every issue."

Santorum's wins dealt a huge blow to conservative rival Newt Gingrich.

Pressure is growing on Gingrich to drop out so Santorum can consolidate conservatives in challenging leading candidate Mitt Romney, who finished third in both states.

But Gingrich said he was staying in the race, and questioned Romney's tag of 'front runner'.

(SOUNDBITE) (English) NEWT GINGRICH, REPUBLICAN PRESIDENTIAL CANDIDATE:

"The fact is, in both states, the conservative candidates got nearly 70 percent of the vote and if you're the front-runner and keep coming in third, you're not much of a front-runner."

Romney though is still way ahead of his rivals - entering Tuesday's contests, with more than 450 delegates, over twice as many as Santorum and far more than Gingrich.

Simon Hanna, Reuters.