With more than 50,000 delegates and media gathered in Denver for the opening of the Democratic National Convention, news of a likely appearance by ailing party lion Sen. Edward Kennedy was the buzz of the lengthy media security line.

It had seemed unlikely that Kennedy, who was diagnosed with brain cancer in May, would be healthy enough to travel to the convention, but by Monday morning most news organizations were reporting that he would appear during a planned tribute to him on the opening night of the four-day convention.

“He is definitely planning to be here,” one Kennedy family confidant told the Boston Globe. “The whole Kennedy family will be in a special section. It should be quite a moment.”

Although the Massachusetts senior senator is in Denver, it was still unclear if he would simply appear in the convention hall tonight or actually address the delegates.

The scion of one the most influential party families, Kennedy’s endorsement of presumptive nominee Sen. Barack Obama has been seen as one of the critical moments of the campaign and helped solidify his candidacy against the better-established Sen. Hillary Clinton.

For the party activists in the hall, the moment is expected to be electrifying.

“Expect a thunderous reception when he takes the stage at the conclusion of the video,” ABC News reported Monday morning. “It’s likely to be the emotional high point of the evening — if not of the entire convention.”