US Republican presidential candidates
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Republican candidates gear up for Super Tuesday

6 March 2012 Last updated at 14:15 GMT

It is the biggest and busiest day of the race to choose a Republican candidate to challenge Barack Obama for the US presidency in November.

Four candidates, Mitt Romney, Rick Santorum, Ron Paul and Newt Gingrich, are competing in ten states on what is known as Super Tuesday.

The BBC's Steve Kingstone reports.