Treasury building in Washington.

Two bond rating agencies are warning Congress about the negative implications of failing to raise the debt ceiling, which will be reached sometime around Sept. 30, when Congress also has to set spending levels for the next fiscal year or risk a government shutdown.

(Related: Bond Experts Warn of Danger of Debt Ceiling ‘Turmoil’)

Complicating matters are threats by President Donald Trump to shut down the government if Congress doesn’t include in its spending measure money to pay for a border wall with Mexico.

(Related: Inaction in Washington Weighing on Economy: S&P)

Fitch Ratings is taking the more dramatic stance on the debt ceiling, noting that if it’s “not raised in a timely manner prior to the so-called ‘x date’” — the date by which the federal government would have to prioritize debt service payments over other obligations — it would review the sovereign rating of the U.S., “with potentially negative implications.”

Moody’s says such prioritization “would not affect the U.S. sovereign rating because they only the risk of default and loss on government debt, not the risk of a delayed payment.” But Moody’s notes that such a delay would not be without cost.

“Without authorization to increase borrowing, the government would have to delay or reduce 14% of total spending,” which would result in shutting down “some government operations.” If a debt payment was missed, however, that would have negative rating implications, according to Moody’s.

Congress returns to the Capitol on Sept. 5 following its summer break. House Speaker Paul Ryan, R-Wis., and Senate Majority Leader Mitch McConnell (R-Ky.) have both said this week that Congress will raise the debt ceiling in time. “There is zero chance — no chance — we won’t raise the debt ceiling. No chance,” said McConnell on Monday.

Treasury Secretary Steven Mnuchin, who was with McConnell on Monday, also said the ceiling would be raised in time, but he’s been pushing for a “clean” bill with no spending reforms attached, which is not what some conservative congressional Republicans want.

Meanwhile, Trump attacked both Ryan and McConnell in a tweet on Thursday, railing that their failure to include the debt ceiling increase in a Veterans Administration bill that recently passed has created “a mess” because Democrats could hold up passage.

The Senate needs 60 votes to pass the debt ceiling increase, and since Republicans hold just 52 seats they need some Democratic support.

S&P has not officially weighed in on the debt ceiling/debt rating debate, but the head of sovereign ratings in the Americas, Roberto Sifon-Arevalo, emailed a Bloomberg reporter that “if the debt ceiling is not raised in a timely way, we expect, at a AA+ level of confidence, that the government will take necessary measures to avoid default on the debt which our ratings address,” similar to what Moody’s has said.

In 2011, S&P downgraded the U.S sovereign rating to one notch below AAA due to “political brinkmanship” in the debate over the debt, which it said had impaired the government’s ability to manage its finances.

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