Explainer: Now What Happens to His Votes?

With John Edwards out of the race, the big question is who his supporters are likely to back, Barack Obama or Hillary Clinton. A national poll last week by the Los Angeles Times reported that a slim majority of his supporters preferred Clinton over Obama, especially on the economy. But the largest base of Edwards' support came from white males, and in primaries to date Obama has won more of their vote than Clinton, by around 10 percentage points.

The more important question is how Edwards' exit upsets calculations of the mechanics of winning delegates to the party's national convention.

Under the rules of the Democratic party, candidates must pass a 15% voting threshold in a primary in order to gain delegates. Although the Florida primary was stripped of its importance, in the event Edwards would have failed to pick up a single delegate, despite winning 14.4% of the vote to Clinton's 49.7% and Obama's 33%. Instead his votes would have been discounted.

If his sub-15% result had been repeated throughout Super Tuesday then Clinton would have benefited hugely. In that case his exit now helps Obama.

But one Democratic consultant in Washington speculated that Edwards' white male base may represent a rump of the Democratic party unmoved by the attractions of voting for either a women or a black candidate. Exit polls of South Carolina Democratic voters found that one in four voters still think the country isn't ready for either a black or female president.