DENVER -- Wolf Blitzer is a John Legend fan, or perhaps he was just trying to appear "hip."

After CNN aired a live performance of Legend's new song, "If You're Out There," from the floor of the Democratic National Convention, the 60-year-old Blitzer promised to continue to interrupt the network's reporting or analysis for musical acts as good as Legend.

Legend was the most visible of the entertainers who flowed into Denver for the convention, which opened Monday. A choir backed him for the song that fits neatly with Barack Obama's campaign themes.

"We've been looking for the world to change," Legend sang. "If you're out there, sing along with me. Stand up and say it loud. Tomorrow's starting now."

Among other celebrities spotted on the first day of the convention:

-- Danny Glover, wearing a jacket over a Martin Luther King Jr. shirt, who talked about unions at a Creative Coalition event.

-- Kal Penn of the "Harold & Kumar" movies and the TV series "House," who worked for a good part of the day as a "delegate whip."

-- Cyndi Lauper was interviewed on the convention floor.

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-- Spike Lee arrived at the VIP section of the Pepsi Center just before the first-night prime-time convention slot.

-- A short while later, the Creative Coalition delegation arrived, with Alan Cumming wearing a brown Obama shirt and Susan Sarandon sporting an Obama button. Also at the Pepsi Center after a day of Creative Coalition luncheons and gatherings: Anne Hathaway, Cumming, Tim Daly, Rachael Leigh Cook and Josh Lucas.

-- Robert Randolph & The Family Band and The Fray performed for convention-goers.

-- "American Idol" alum Chris Daughtry was in the audience at a Rock the Vote concert at the city's opera house, which featured Jakob Dylan, NERD and Fall Out Boy.

-- During Fall Out Boy's set, Pete Wentz told the crowd: "We came all the way from Chicago, like somebody else you know." Wentz and Patrick Stump later said they learned that Joe Biden would be Obama's running mate while bowling with Diddy. And there's an even more personal connection: Wentz said his parents met while working for Biden. Wentz said his father told him before he left for Denver, "`When you bump into Biden, make sure you tell him that. He'll remember.' I'm like, 'Uh, that's not really how this works."'