O'Malley is the only governor on a list of more than 30 high-profile Democrats hosting a Colbert Busch fundraiser in Washington, D.C. later this month, according to an invitation to the event obtained by The Baltimore Sun.
Colbert will be a featured guest at the "Colberts United!" benefit, said the invitation, which makes generous use of exclamation points.
O'Malley stumped a little for Colbert Busch last month when he gave the keynote address at a conference of South Carolina Democrats.
Colbert Busch, a Democrat, faces Republican former South Carolina Gov. Mark Sanford, who made headlines outside the state for traveling with his mistress to Argentina while he was purportedly hiking on the Appalachian Trail. He is now engaged to her.
Twenty-nine Democratic representatives, including House Minority Leader Steny Hoyer, and six senators are also hosts to the April 15. Another Colbert Busch benefit will be held in New York the following week.