"Frankly, what's disturbing about it is that [Obama] signed a piece of paper back when he was a longshot candidate," McCain said. "And he signed it, said I won't -- I will take public financing for the presidential campaign if John McCain will. I mean, it's a living document."
McCain was referring to Obama's answer of "yes" on a "Common Cause" questionnaire when asked, if nominated for president and his opponent agreed, would he participate in public financing. The senator reversed course on the pledge after it was clear his eye-popping fundraising could give him tens of millions of dollars more than McCain.
Speaking to reporters earlier in the day in Palm Beach, Fla., McCain tried to make the Obama network buy seem grandiose, calling the spot a "gauzy, feel-good commercial" that was "paid for with broken promises."
With an 8 p.m. ET start time, Obama's production was the lead-in to Fox's World Series coverage, and McCain chided Obama for buying the network while the fall classic was on the schedule.
"It used to be that only rain or some other act of God could delay the World Series, but I guess the network execs figured an Obama infomercial was close enough," McCain said.
Fox Broadcasting denied that the Obama ad delayed the start of the game, saying only the Joe Buck-led pre-game portion of the broadcast was affected, a network executive told Politico.
Candidates spend the biggest amount of their campaign cash on television advertising. Propelled by record-breaking fundraising, Obama is on his way to spending more than $200 million on television ads during his general election fight with McCain. As of Oct. 17, Obama had spent $167.3 million on ads during his general election compared to McCain's $107.9 million, according to the ad tracking firm Campaign Media Analysis Group.
There's also free media that the candidates use to get out their message. That's why McCain was slamming Obama on taxes during the Wednesday talk with King.
"Sen. Obama clearly has talked about for years, redistributive policies," McCain said. "And that's not the way we can create wealth in America. That's not the way we grow our economy. That's not the way we create jobs.
"And when small business people see that half of their income, half of the income of small businesses, is going to be taxed by Sen. Obama, then they're very upset with it," McCain said.
McCain knows that recent polls show Obama has gotten the upper hand on taxes, and McCain has argued his plans to reduce taxes and cut wasteful spending, as he has attacked the Obama economic plan as a promise of wealth redistribution.
According to a Comedy Central transcript of "The Daily Show," with an easy setup from host Jon Stewart, Obama jokes about his white half being confused about who to vote for.
"Are you concerned in some respects -- I don't know how to bring this up," Stewart said. "Your mother is from Kansas, father African: Are you concerned that you may go into the voting booth and -- "
"I wont know what to do," Obama joked.
" -- Your white half will all of a sudden decide, 'I can't do this!'" Stewart said.
"Yeah," Obama said. "It's a problem. ... I've been going though therapy to make sure that I vote properly on the 4th."
ABC News' Jake Tapper and Sunlen Miller contributed to this report.