The late-night comic banged away at McCain on Thursday from the opening of his monologue.
"You're here on a good night," he told the audience. "So far none of our guests have canceled."
He talked about daredevil David Blaine's feat of hanging upside down in New York's Central Park for 60 hours.
"They just left the guy hanging there," he said. "It's the same thing McCain did to me last night."
He described socialite Paris Hilton _ Thursday's guest whose celebrity was once used in a McCain campaign ad to mock Obama _ as McCain's first choice for a running mate.
"Here's how it works: you don't come to see me? You don't come to see me? Well, we might not see you on Inauguration Day," Letterman said.
Noting that McCain wanted to postpone Friday's first debate with Barack Obama, Letterman said running mate Sarah Palin wanted to put off her debate with Democrat Joe Biden until after Election Day. Letterman said McCain taking Palin to meet world leaders at the United Nations was like "take-your-daughter-to-work day."
Letterman's Top 10 list was "surprising facts about Sarah Palin," read by citizens of Wasilla, Alaska, where she was once mayor.
No. 10: Palin "sometimes calls John McCain grandpa."