“I didn’t know you were Catholic,” Ms. Pelosi said, a wry reference to Mr. Paulson’s kneeling, according to someone who observed the exchange. She went on: “It’s not me blowing this up, it’s the Republicans.”

Mr. Paulson sighed. “I know. I know.”

It was the very outcome the White House had said it intended to avoid, with partisan presidential politics appearing to trample what had been exceedingly delicate Congressional negotiations.

Senator Christopher J. Dodd, Democrat of Connecticut and chairman of the Senate banking committee, denounced the session as “a rescue plan for John McCain” in an interview on CNN, and proclaimed it a waste of precious hours that could have been spent negotiating.