Dean, the former Vermont governor who once led the Democratic hopefuls in the polls, suspended his campaign February 18 after a string of primary and caucus losses.

CNN: Cuomos endorse Kerry

Romney has long been thought of as the Republican frontrunner, but his struggles to string together wins in the primary season threaten to drag the battle for the nomination into a protracted delegate fight.

MSN: Romney goes two-for-two on primary night

Having failed to win in Iowa, where he had camped out since 2004, and in South Carolina, his birth state and the only primary he won four years ago, Edwards was destined for a string of third-place finishes had he stayed in the race.

NPR: It's Super Tuesday. How Did We Get Here?