"The work begins anew, the hope rises again and the dream lives on," Kennedy said in a strong voice, reprising the final line of a memorable 1980 speech that brought a different convention to its feet. The senator has been undergoing treatment for a malignant brain tumor.

Convention planners hoped a prime time address by Obama's wife, Michelle, would begin the work of casting the Illinois senator as a leader with classic American values.

Among them, she said in prepared remarks: "that you work hard for what you want in life, that your word is your bond and you do what you say you're going to do, that you treat people with dignity and respect, even if you don't know them, and even if you don't agree with them."

The convention opened as polls underscored the closeness of the race with Republican John McCain, and there was no underestimating the challenges as Obama bids to become the nation's first black president.

He faces lingering divisions from a fierce battle with Hillary Rodham Clinton for the nomination, tough ads by McCain and his Republican allies, and a reminder that racism, too, could play a role.
Copyright 2008 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.