Indiana superdelegate Joe Andrew, who served under Bill Clinton, switched his allegiance from Hillary Clinton to Barack Obama today, and encouraged other Dems. unite behind him. Andrew was the Democratic National Committee Chairman in early 2000. He’s sent out lengthy letters to each of the superdelegates explaining his decision. Here are some excerpts:

Andrew said in his letter that he is switching his support because “a vote for Hillary Clinton is a vote to continue this process, and a vote to continue this process is a vote that assists (Republican) John McCain.”

“While I was hopeful that a long, contested primary season would invigorate our party, the polls show that the tone and temperature of the race is now hurting us,” Andrew wrote. “John McCain, without doing much of anything, is now competitive against both of our remaining candidates. We are doing his work for him and distracting Americans from the issues that really affect all of our lives.”

Andrew was never approached by the Obama campaign to switch, he said he was impressed with Obama’s stand against the gas tax (when Clinton and McCain supported it) and how Obama was handling the Rev. Write controversy. The letters implied that Clinton hasn’t taken a principled stand on the issues.

The timing couldn’t be worse for Clinton; she’s losing a prominent ally only days before the Indiana primary. It’s also far worse to lose a delegate this way than to compete for an uncommitted delegate. Andrew showed he lost faith in her chances and abandoned her party. Obama now trails Clinton by just 16 superdelegates, and others might be swayed once they find Andrew’s letter in their mailbox.

Still, analysts question whether Andrews endorsement will have any influencing power. Just as John Kerry made flip-flopping unfashionable in 2004, Andrews “wobbling” between the two candidates could bring more negative attention to himself than to Clinton.