Romney duels a surging Santorum

8 February 2012 Last updated at 00:59 GMT The Romney campaign has struggled to shake doubts about his candidacy among conservatives Mitt Romney has been fighting off a surging Rick Santorum as voters in three US states gather to pick a Republican presidential nominee.

Social conservative Mr Santorum was the pollsters' favourite in Minnesota and Missouri's contests, although Mr Romney is expected to win in Colorado.

Mr Romney, whose credentials are distrusted by some conservatives, was trying to lower expectations.

The eventual nominee will go on to face Barack Obama in November's election.

Newt Gingrich, still Mr Romney's main challenger, has campaigned lightly in the three states voting on Tuesday, and does not even appear on Missouri's ballot.

In Minnesota and Missouri - states with significant blocs of Tea Party and evangelical Christian voters respectively - Mr Santorum has been gaining ground.

A Public Policy Polling survey on Tuesday placed him on 33% in Minnesota, ahead of Mr Romney by nine percentage points, and on 45% in Missouri, a 13-point lead.

According to the same opinion poll, Mr Romney, a former Massachusetts governor, led the pack in Colorado at 37%, a 10-point lead over Mr Santorum, his nearest competitor in that state.

Texas Congressman Ron Paul was at the back of the field in all three states, although a Reuters/Ipsos poll on Tuesday showed him surging into second place nationally.

Pitching himself as the only true conservative in the presidential race, Mr Santorum made a last-minute flurry of campaign appearances on Tuesday in Colorado, Minnesota and Missouri.

The former Pennsylvania senator, who has not won a contest since grinding out a narrow win in Iowa's caucuses back in January, is still considered a long-shot candidate.

Mr Romney, meanwhile, has been campaigning hard on abortion, religious freedom and gay marriage in an intensified effort to win over social conservatives ahead of Minnesota and Colorado's caucuses.

During his first run for the Republican presidential nomination back in 2008, Mr Romney was victorious in both Colorado and Minnesota.

But both states are perceived to have moved to the right since then, so doubts over his Mormon faith and political record as governor of a liberal state could cost him.

Playing down the significance of Tuesday's votes, Romney campaign political director Rich Beeson said: "Mitt Romney is not going to win every contest. John McCain [the 2008 Republican nominee] lost 19 states in 2008, and we expect our opponents will notch a few wins, too."

In Minnesota, 37 delegates are at stake with 33 up for grabs in Colorado. The primary in Missouri is being dubbed a "beauty contest" since it will actually allocate its delegates next month.

Mr Gingrich campaigned on Tuesday in Ohio, one of 10 states that will vote on Super Tuesday early next month.

Correspondents say the former House of Representatives Speaker's game plan is to ride out February and hang on until March when Southern states where he stands a better chance of success come into play.

Before Tuesday's votes, Mr Romney had 101 of the 1,144 delegates needed to clinch the nomination at the Republican Party convention in August, according to an Associated Press news agency tally.

In second place, Mr Gingrich was on 32 delegates, Mr Santorum 17 and Mr Paul nine.

Mr Romney has racked up the most victories in this year's election race, with resounding wins in New Hampshire, Florida and Nevada.