The Trust for the National Mall is a philanthropy with its shit together: It’s got big-time corporate backing, an influential board, and a loyal under-40 following. For the three years since its launch in 2007, however, the group has been missing one key fundraising element: Star power. (Whitney Houston doesn’t count).

Caroline Cunningham, the Trust’s president, has been puzzling about this. She was hoping George Clooney might be interested; his father is a professor at American University and the actor finds himself in D.C. not infrequently.

What she ultimately got, though, trumps even Clooney. On Monday, Jon Stewart said on National Public Radio that he would ask attendees of the March to Restore Sanity to write checks to the Trust. His website makes the best case out there:

We feel it’s important to preserve this historic site for future rallies and for future Americans to rally on! And let’s face it; we’re a little afraid that you might make a mess. We really, really hope you don’t — we hope that, in the name of sanity and reasonableness, you won’t be dicks and will actually pick up after yourselves. But just in case you accidentally, like, put a beverage down on the Mall’s coffee table without using a coaster, we figure that giving a little something back to the National Mall might, at least, soften the blow. But really, mainly, it’s about the “preserving the historic site” thing.