We wake this morning in a new world.

The news this morning is that a number of Hillary Clinton’s pledged superdelegates are switching their allegiance to Barack Obama. The group, led by civil-rights veteran and Georgia Congressman John Lewis, say they are reacting to the popular primary votes in their state, but they are also bowing to what is becoming more and more clear.

Mr. Obama is leading Ms. Clinton in fundraising, in elected delegates and in polls he matches up better against John McCain for the general election. Yesterday David Wilhelm, Bill Clinton’s 1992 campaign manager, announced his support for Mr. Obama.

Timing now is of greatest importance to professional politicians. Candidates love no one so much as early supporters, who were on board before anyone thought they could win. They also love those who decide in their favor when the contest hangs in the balance, those who push the scales to their side. In this case, Mr. Lewis.

Sensing a winner in the race, we can now expect professional pols who have until now been on the fence (or on the Clinton side of the fence) to rush to Mr. Obama, hoping to get on the bandwagon before everyone starts calling it a bandwagon.

But it’s too late for that. It’s a bandwagon.