Ratings giant DBRS solidified its commitment to keeping the U.S. sovereign debt rating at AAA … at least for now.

Obviously, with all that’s happening on Capitol Hill the firm’s rating could shift again. All one has to do is remember the summer of 2011 when gridlock over raising the debt ceiling led Standard & Poor’s to lower the nation’s credit rating to 'AA+'—a scenario that stalled the economy and led to a massive debate over the role of Congress, the president ... and even S&P during debt ceiling talks.

But no one’s doubting the U.S. credit rating is in trouble if deadlines are missed this time around.

Once again, it’s up to Congress and the president, DBRS says.

If Congress or the president fail to end the shutdown in time to thwart a breach of the debt ceiling – and a full default happens – DBRS expects pain for the national economy.

The good news: They don’t think Congress or the president will let that happen. (Apparently, DBRS has a higher opinion of Congress and the president than most Americans).

"DBRS expects that the U.S. Congress will reach an agreement to end the shutdown of the federal government and avert a default on its debt," the ratings giant said. "For this reason, DBRS is maintaining its AAA rating on the United States."

Yet, time is of the essence – the longer this drags on, the more dangerous it becomes, DBRS suggested in its latest note.

If DBRS sees no agreement on raising the statutory limit on the debt ceiling, the firm may be forced to place its U.S. sovereign debt rating "under review with negative implications."

"If the U.S. misses a debt payment, DBRS would assign a selective default rating to the affected securities, as long as DBRS expects the Treasury to meet its other obligations in a timely manner,” the ratings firm explained. "If there is a full-fledged default involving a wide array of securities, the magnitude of the downgrade of the United States would be more significant."

For now, DBRS says the country’s overall strength is keeping it at AAA. But the current standoff – if extensive and uncompromising – could weaken the nation’s creditworthiness.

The takeway: If Congress reaches an agreement to avert a default before the debt ceiling is breached mid-month, the U.S. credit rating will be safe.

If not, expect pain, DBRS says.

"There is no question that the damage from a U.S. default would have wide repercussions on U.S. and global growth prospects, investor confidence, and the stability of the international financial system,” the ratings giant concluded.

The good news is S&P – the firm that already knocked down the U.S. sovereign debt rating – has no plans to go lower than AA+ for now.

"We believe there is a less than 1-in-3 chance of a rating change over the next two years," S&P explained.

But lawmakers may want to heed S&P's warnings. Political gridlock is what caused its 2011 downgrade in the first place.

"This sort of political brinkmanship is the dominant reason the rating is no longer AAA," S&P said. Ouch.