"I'm excited to be around other people who are fed up with the dominant voice being Bill O'Reilly or Glenn Beck," said Reilly, complaining that conservative-oriented Fox News has "the loudest bullhorn" ahead of Tuesday's critical midterm election.
There is little disagreement that Saturday's rally - which organizers have forecast to draw 60,000 people but which seems on track to be even larger - is the politically tinged event of the fall for the large demographic of Stewart and Colbert fans, who tend to be younger, well-informed and to the left of the political divide.
But - in perhaps a commentary on the absurdness of the American political moment - there remains little agreement over what the rally is actually about, even among those who've plunked down hundreds of dollars for train tickets and motel rooms.
Is it, indeed, an in-your-face rejoinder to conservatives Beck and Sarah Palin, who drew a large throng to the Lincoln Memorial on the other end of the Mall for their Restoring Honor rally in late August?
Is it nothing more than a big outdoor comedy show with rock bands on a glorious October day - with no grander purpose than biting satire, and perhaps moving a few copies of Stewart's new book?
Or, is it what Stewart himself has said, "a rally for the people who've been too busy to go to rallies, who actually have lives and families and jobs (or are looking for jobs) - not so much the Silent Majority as the Busy Majority"?
As they say on Facebook - where as of yesterday some 221,543 people claimed they would be attending - it's complicated.