A new national CBS News poll shows a close three-man race for the Republican nomination for president among Herman Cain, Mitt Romney, and Newt Gingrich. Cain received 18 percent support, while Romney and Gingrich are both tied at 15 percent. That shows a decrease in support for Cain and Romney, who earned 25 and 21 percent, respectively, in a CBS News poll in October. Gingrich, meanwhile, gained five points from his 10 percent haul in that October poll.

Overall, Gingrich has improved in the polls within the last 30 days, including in polls of Republican voters in important early primary states like Iowa and South Carolina. And in important swing states like Ohio, Gingrich is performing well.