May 5: The first of more than a dozen GOP debates is held in Greenville, S.C.
May 11: Newt Gingrich enters the race
May 13: Ron Paul begins his third presidential campaign
May 15: Gingrich dismisses the House GOP budget as "right-wing social engineering"
May 21: Herman Cain enters the race
May 22: Indiana Governor Mitch Daniels says he won't run
May 23: Tim Pawlenty enters the race
June 2: Already leading in the polls, Mitt Romney enters the race
June 6: Rick Santorum enters the race
June 9: Top Gingrich staffers resign after the candidate goes...