The battleground for the Republican presidential nomination heads to the deep South for Tuesday's primaries in Alabama and Mississippi after hardline conservative Rick Santorum won Saturday's Kansas caucus.
Republican presidential candidate Rick Santorum and his wife, Karen, greet supporters during a rally in Springfield, Missouri. Santorum won 51 percent of the vote in Kansas, compared with 21 percent for Mitt Romney
Frontrunner Mitt Romney has consolidated his position with a string of Super Tuesday victories but faces a tough test in the South, and Santorum's solid win in Kansas kept the Christian conservative's hopes alive.
Former Pennsylvania senator Santorum won handily in Kansas with 51 percent of the vote, compared with 21 percent for Romney, 14 percent for former House speaker Newt Gingrich, and 13 percent for congressman Ron Paul, final results showed.
While Romney is the national frontrunner, there is still no definitive candidate to take on Democratic President Barack Obama in the November election.
Santorum spokesman Hogan Gidley said the Kansas victory proved the candidate's conservative credentials.
"We are very pleased to see the Santorum surge sweeping through the Jayhawk State," he said. "This is a great win for the campaign and further evidence that conservatives and Tea Party loyalists are uniting behind Rick as the true, consistent conservative in this race."
The Santorum win in Kansas was offset in part by Romney victories in Wyoming and in the US territories of Guam, Northern Mariana Islands and Virgin Islands.
Gingrich meanwhile stopped campaigning in Kansas to focus this week solely on the South. He accused Obama of "declaring war on the Catholic Church and every right-to-life institution" with a rule requiring religious organizations, such as Catholic hospitals, to include contraception in their employees' health plans.
Gingrich told supporters that "the right to bear arms came from God," through the Declaration of Independence and the constitution.
But Romney was campaigning hard in Dixie and received endorsements from many of Mississippi's top Republican leaders, including most recently Governor Phil Bryant.
A new poll shows Romney leading the Republican pack in Mississippi by eight points -- but some think that the enthusiasm just isn't there for the former Massachusetts governor.
"I don't believe that Romney will be able to win in Mississippi or in Alabama," said Troy Gibson, associate professor of political science at the University of Southern Mississippi. "I just don't think he has the enthusiastic base that he would need to pull those out."
Gibson thinks Romney's best chance is if the conservative vote is evenly split between Santorum and Gingrich -- and the new poll released by Rasmussen Reports shows just that.
The media group said Saturday that in a new statewide telephone survey of likely GOP primary voters, Mitt Romney had 35 percent of the vote, followed by Santorum and Gingrich with 27 each. Paul trails with six percent, and four percent are undecided, Rasmussen said.
Gibson predicts Santorum will win narrowly, because of his greater appeal to Mississippi's large evangelical community. He said the state's population is around 40 to 50 percent evangelical, and 80 percent of the Republican base is evangelical.
"Not many other states can match the conservatism of the typical Mississippi Republican primary voter," he said.
Though Romney consolidated his pole position in this week's slew of votes, he failed to knock either Santorum or Gingrich out of the race. Paul, a Libertarian Texas representative, is also hanging on, though he has yet to win a single contest.
Romney has won more than a third of the 1,144 delegates needed to secure the nomination, after 25 contests in the state-by-state Republican race. Santorum won 33 of the 40 Kansas delegates, as Romney added seven.
Big prizes are at stake on Tuesday, when Alabama, with 50 delegates, Mississippi (40) and Hawaii (20) go to the polls.
"Santorum's social conservatism would be expected to play well with deep Southern voters," Charles Franklin, co-founder of pollster.com and a professor at Marquette University Law School, told AFP.
"But, stylistically, Gingrich with his long history in the South maybe is a little more appealing than Santorum's Yankee charm from Pennsylvania."
But while Republicans keep slugging it out, President Obama appears to be gaining support among key constituencies.
Several recent polls have shown that Obama's approval rating has jumped among women since December, from 43 percent to 53 percent, and that the president would enjoy substantial leads among women in hypothetical matchups against either Romney or Santorum.
In a national Pew Research Center poll last month, Obama led Romney by eight percentage points and Santorum by 10 percentage points. However, he was ahead among female voters by a whopping 59 percent to 38 percent over either Republican.