This past week was an eventful one for the Republican 2012 presidential hopeful field. Former House speaker Newt Gingrich and Congressman Ron Paul announced that they would run, former Arkansas Gov. Mike Huckabee announced he wouldn't, and former Massachusetts Gov. Mitt Romney tried to tackle his health care dilemma. NPR's Mara Liasson brings us up to date on the 2012 candidates for the Republican presidential nomination.