Sen. Hillary Rodham Clinton gave her fellow New York Democrats a preview of her likely speech Tuesday night in Denver, calling for unity behind presumptive nominee Sen. Barack Obama (Ill.) even as she acknowledged discontent among her supporters that she is not on the ticket.

“I ask each of you to work as hard for Barack and Joe Biden as you did for me,” she said, referencing the Senator from Delaware who is Obama’s running mate. “The Democratic Party is like a family and this is like a family reunion. We were not all on the same side as Democrats, but we are now!”

In another move intended to promote unity among her delegates, Clinton is expected on Wednesday afternoon to tell her pledged supporters that they are free to vote for Obama during the first roll call, as she will do, sources confirmed. On Wednesday evening, Clinton is expected to get a symbolic roll-call vote intended to mark her historic candidacy.

Clinton told New Yorkers that they must unite behind her former rival because, “We cannot afford four more years of [President] George Bush’s failed policies for America, and that is exactly what we would get with John McCain.”

She also took the Arizona Republican Senator’s campaign to task for releasing a new ad that solicits her supporters. “I’m Hillary Clinton and I do not approve that message,” she said.