Rick Santorum campaigning in Polk City, Iowa
Media playback is unsupported on your device
Video

Iowa caucuses: Rick Santorum sees support surge

Republican presidential candidates are making their final pitches to voters in Iowa on the last full day of campaigning before the state's caucuses.

The Iowan vote is the first contest for the candidates hoping to be chosen to challenge President Barack Obama in November's election.

Mitt Romney is the front-runner of the group, but in recent days Rick Santorum has gained fresh support.

Katty Kay reports from Polk City in Iowa.

Go to next video: Science of Politics: Iowa Caucus