DENVER — Senator Kennedy told a cheering Democratic National Convention tonight that this is “a season of hope” for a stronger future in America, his wave familiar, his voice firm, despite his struggle against brain cancer.

And he added: “I pledge to you that I will be there next January on the floor of the United States Senate.”

That had special meaning given the bleak prognosis he faces with his disease.

“The hope rises again and the dream lives on,” he said after his seven minutes at the microphone, minutes of high and unexpected drama for delegates waving thousands of Kennedy signs, cheering as he came and as he stepped away into the arms of his wife Vicki.

“My fellow Democrats, my fellow Americans, it is so wonderful to be here,” he said. “And nothing, nothing is going to keep me away from this special gathering …”

He flew to Denver last night, and his first stop was a hospital, where doctors examined him. His physicians had been wary of the trip, especially his exposure to crowds, given the weakness of his immune system after weeks of chemotherapy and radiation treatments. The brain cancer was diagnosed after he collapsed in May in Hyannis Port, Mass. After brain surgery in June, he had remained at home, save for a brief trip to Washington to cast a Senate vote on July 10 for Medicare legislation that had been stalled in deadlock.