In Historic Vote, Obama Officially Claims Democratic Nomination

Ritter said those struggles must be the focus of both Biden's speech tonight and Obama's tomorrow at Invesco Field.

"Hillary Clinton could not have delivered a more genuine and impassioned message as to why this country needs Barack Obama as president of the United States," he said.

But Obama's plans for middle-class tax cuts, the development of a clean-energy economy and universal health care has been lost in the media's fascination with Obama's rhetoric and image, the governor said.

"He's a brilliant speaker. His rhetoric is fabulous. He really is inspirational," Ritter said, but that is not enough. "He has to convince people he has a plan for the economy. He has to get in the weeds."

And with early voting starting in Colorado Oct. 5, Obama does not have much time, he added.

Biden, tapped as a running mate in part because of his experience as chairman of the Senate Foreign Relations Committee, will cap a night dedicated to national and homeland security.

But he was also tapped because of his ability to hit back at McCain, who he counts as a friend, colleague and sometime rival from the Senate Armed Services Committee. Susan Rice, a senior Obama adviser on foreign policy, would not comment on Biden's speech, but she did lash out at McCain's newest attack ad, which accuses Obama of dimissing Iran as a "tiny" threat to the United States.