The vote of the Democratic rules committee not to seat the entire Michigan and Florida delegations — as Hillary had wanted — signals the end of the domination of the Democratic Party by Bill and Hillary Clinton. It began when Bill won the California primary in 1992 and ended this past weekend, on May 31, 2008. During this period, nothing moved unless the Clintons OK’d it. Now the party has declared its independence, shaking off their family fiefdom.

There is a lot more involved than just the fact that Hillary lost the primaries to Obama and trails him among elected and superdelegates. Obama will now have an easy glide path to the nomination, which he should wrap up by June 4.

But the power in the party has moved from the Clinton family to a combination of institutional Democrats, labor unions, and strong left-wing groups. The massive grassroots structure, built up by MoveOn.org and amplified by Obama's online campaign, has become the dominant force in the party.

But they do not rule alone. The Clinton defeats have liberated the unions and state Democratic parties, once under the Clintons' thumb, to become independent power centers working in coalitions with each other and with the radical left. The Democratic Party is now up for grabs. If Obama is elected, he will impose his own vision on it. But if McCain wins, this weekend’s vote sets up a power struggle that should be interesting.