Massachusetts Sen. Edward Kennedy, who is battling brain cancer, did not attend a delegation breakfast Monday morning as expected, but he is still planning to go to a convention tribute to him on the event's opening night and may speak, his Senate office told FOX News.

Kennedy arrived in Denver Sunday night and got a checkup at a local hospital. He plans to watch the video tribute at the Pepsi Center and may address the convention if he feels up to it, said a senior Democratic official who talked on the condition of anonymity.

"He's truly humbled by the outpouring of support, and wouldn't miss it for anything in the world," his office said in a statement.

It did not explain why he missed the breakfast.

Kennedy, who is being treated for a malignant brain tumor, is a beloved figure within the party, and his last-minute appearance at the Democratic National Convention is a way toward unification amid signs of acrimony between delegates for Barack Obama and Hillary Clinton. Kennedy endorsed Obama in January.

Kennedy's health is described as fragile but not deteriorating. His planned appearance will bear few of the tell-tale signs of the toll chemotherapy sometimes takes on cancer patients. It will be the first time he's been seen in a political environment in at least a month.

Award-winning documentary filmmaker Ken Burns directed the video tribute, which will be introduced by Kennedy's niece, Caroline Kennedy. FOX News has been told one aspect of the tribute shows Kennedy at the helm of a sailboat, his family riding along and responding to his "orders" to set the vessel on course.

The video tribute to Kennedy, who challenged President Jimmy Carter in 1980 and set fire to the liberal wing of the party, is expected to be a highly emotional moment.

A culmination of the event’s opening night could be Kennedy’s appearance on stage after the video tribute concludes, a moment that would inevitably bring the house down.

The Associated Press contributed to this report.