“Just as he discussed with the Republican caucus, the president highlighted the need for both parties to work together to take a balanced approach to deficit reduction, one that allows us to live within our means without hurting our ability to invest in the future or burdening our middle class or seniors,” an administration official said.

House Democrats said they would support Mr. Obama if he reached a compromise with Republicans that included long-term spending cuts, but not to Medicare benefits, as well as higher tax revenues, according to those briefed on the meeting.

The House speaker, John A. Boehner, said in a statement, “The White House needs to get serious right now about dealing with our deficit and debt.” He interpreted the Moody’s report as bolstering his contention that “a credible agreement means the spending cuts must exceed the debt-limit increase.”

Moody’s, however, made no mention of how a deficit-reduction deal should be structured.

The Moody’s report was unexpected. In April, Standard & Poor’s lowered its outlook for the AAA rating on United States debt — but not the rating itself — to negative from stable. Moody’s cautionary note was more pointed in that it was pegged to the current political maneuvering over the debt limit and it urged a resolution weeks sooner than the White House and Congressional leaders were aiming for.

Its warning was two-pronged. First, Moody’s said, if Congress does not increase the Treasury’s borrowing authority in coming weeks, the nation’s credit rating may be lowered “due to the very small but rising risk of a short-lived default.” That is likely to translate into higher interest rates at a time when the recovery shows signs of slowing again.

And second, Moody’s said, with an implicit slap at both parties, that whether the United States keeps its triple-A rating “will depend on the outcome of negotiations on deficit reduction.”

“Although Moody’s fully expected political wrangling prior to an increase in the statutory debt limit, the degree of entrenchment into conflicting positions has exceeded expectations,” the company’s statement said. “The heightened polarization over the debt limit has increased the odds of a short-lived default.”