A senior U.S. Treasury official Wednesday said a potential U.S. credit rating downgrade isn't influencing the department's debt management plans.

"It doesn't affect our thinking at all," Mary Miller, Treasury's assistant secretary for financial markets, said at a press conference.

Major ratings companies such as Moody's Investors Service and Standard & Poor's Ratings Services last month placed the U.S. prized AAA credit rating on watch for a possible downgrade.

Following a grueling political debate, President Barack Obama on Tuesday signed a new law to eventually lift the government's borrowing limit by $2.4 billion and cut the federal deficit by a similar amount, hours before Treasury was to exhaust its ability to finance its obligations.

Treasury is now largely back to business as usual. Following the new debt ceiling agreement, Moody's took the U.S. off its watch list and affirmed the country's triple-A rating, though the company said the outlook is now negative. Standard & Poor's hasn't changed its stance. Both firms cited large U.S. budget deficits for their concerns.

Miller's comments came as the department said it would issue $72 billion in new debt next week, but noted future auctions may decrease slightly as budget deficits decline. She said Treasury still plans to gradually extend the maturity of its securities portfolio.

The Treasury plans to sell $32 billion in three-year notes on Aug. 9, $24 billion in 10-year notes on Aug. 10, and $16 billion in 30-year bonds on Aug. 11. All of the auctions will settle on Aug. 15.

Treasury has been gradually lengthening the average maturity of the securities it issues--to almost 62 months in July from about 49 months in late 2008, after the federal government flooded the market with shorter-term Treasury bills during the financial crisis.

"Irrespective of anything or any discussion about ratings agencies, our intention is to continue on that path," Miller said.

The Treasury Borrowing Advisory Committee, a key group of senior representatives from investment funds and banks, discussed a potential downgrade at a meeting Tuesday. "None of the members thought a downgrade was imminent," minutes of the meeting, released Wednesday, said.

All together, Treasury expects to borrow $331 billion this quarter, and another $285 billion the next.

The Treasury had to alter one program because of the mechanics of the three-stage debt ceiling increase. Treasury won't restart auctions of bills for a special account at the Federal Reserve, because an immediate resumption of this program would eat too deeply into the first tranche of the debt ceiling increase and reduce flexibility with other borrowing.

The first stage of the new debt ceiling calls for just a $400 billion increase in the borrowing limit.

To maintain flexibility earlier this year as it ran up against the old limit, Treasury cut the Supplementary Financing Account to zero from $200 billion.

Under the supplementary financing program, Treasury sells short-term bills and moves the proceeds into the Federal Reserve's accounts. The money raised by Treasury and transferred to the Fed drains reserves from the banking system.

The Department could still bring back the program when the full $2.4 trillion debt ceiling increase is finished, the official said, a view shared by analysts.

"We suspect that a resumption could take place later this year when the debt ceiling is raised a further $500 billion, or early next year at the latest," said Millan Mulraine, senior U.S. macro strategist at TD Securities. Read More