After an emotional video tribute on the first night of the Democratic National Convention in Denver, an ailing but robust Massachusetts Sen. Edward Kennedy vowed to supporters Monday that he will see Barack Obama take the oath of office on Capitol Hill next January.

"I pledge to you that I will be there next January on the floor of the United States Senate when when we begin to write the next great chapter of American progress," Kennedy told an overwhelmingly enthusiastic crowd.

Thousands on the convention floor held up blue "Kennedy" signs as he shuffled to the stage.

Kennedy seemed almost defiant, smiling, waving and making his pledge.

"It is so wonderful to be here," he declared. "Nothing, nothing was going to keep me away from this special gathering tonight."

A fixture at Democratic conventions for 40 years, Kennedy, who is battling brain cancer, was not expected to attend this one. He pre-taped a message to delegates before making a surprise visit to Denver Sunday night. His last-minute appearance was touted as a way toward unification amid signs of acrimony between delegates for Obama and Hillary Clinton. Kennedy endorsed Obama in January.

Cheers broke out frequently during the video tribute and speech, including chants of "Teddy! Teddy!" But the biggest applause line came near the end of Kennedy's remarks when he talked about passing the torch.

"And this November, the torch will be passed again to a new generation of Americans," he said.

"And so with Barack Obama -- for you and for me, for our country and for our cause – the work begins anew, the hope rises again, and the dream lives on," he said, referencing his 1980 convention speech, where he formally conceded to Jimmy Carter after their hard-fought primary.

The first night of the convention ended with a speech from Michelle Obama.

FOX News' Judson Berger contributed to this report.