The high-profile gathering of political regulars who once fought against Obama serves a dual purpose for Clinton: Show fellow Democrats that she can be a team player, and display her still formidable political strengths for the future. Many of her supporters want her to run for president again.
A Democratic official told The Associated Press Sunday, a day before the convention begins, that she is expected to release her delegates at the Wednesday event. The official spoke on condition of anonymity because the person was not authorized to discuss details publicly.
Asked about Clinton's plans for the event, her spokesman Philippe Reines said it will be "an opportunity for Senator Clinton to see her delegates - many for the first time since the primaries ended, thank them for their hard work and support, and most importantly to encourage them to support and work for Senator Obama as strongly as she has in order to elect him in November."
The New York senator has support among key voting groups that Obama has yet to win over, particularly women, older voters, and working-class voters.
Coming into the convention, many Democrats have wondered exactly how and when Clinton would throw her delegates to Obama, and if that would be a messy, contentious affair.
Republicans are already trying to take advantage of such potential fissures.
John McCain's campaign launched a television ad suggesting rival Barack Obama snubbed Clinton because of her criticism during the Democratic primary fight.
The ad features clips of Clinton, including one in which she accused him of negative campaigning, and a voiceover announcer says: "She won millions of votes but isn't on the ticket. Why? For speaking the truth."
Clinton aides responded that she clearly supports Obama and agrees with him on important issues like health care and the Iraq war, and doesn't agree with McCain on those issues.