Gingrich furious at ex-wife's 'open marriage' claim

The race for the Republican presidential nomination took several twists and turns as Rick Perry dropped out, Newt Gingrich faced stunning allegations from his ex-wife and Mitt Romney struggled to maintain a shaky front-runner's standing.

An aggressive evening debate in North Charleston, in the critical state of South Carolina, site of the next primary vote, capped the bewildering day.