WASHINGTON – After the first-ever downgrade of the U.S. government’s credit rating, the White House said on Saturday that President Barack Obama believes it’s clear Washington “must do better” in tackling the deficit.

While Republicans and Democrats traded blame over Friday’s move by Standard & Poor’s to lower its AAA credit rating, a statement from White House press secretary Jay Carney was muted in tone and did not refer directly to the downgrade.

Administration officials privately called S&P’s analysis flawed. But Obama himself refrained from comment as he spent the weekend at Camp David.

The move by the key credit agency reflected disappointment with Tuesday’s pact hiking the U.S. borrowing limit, which called for roughly $2 trillion in deficit cuts over the next decade. It had previously called for cuts approaching $4 trillion.

In a statement Saturday, Carney called the hard-fought deal “an important step in the right direction.” However, he said “the path to getting there took too long and was at times too divisive. We must do better to make clear our nation’s will, capacity and commitment to work together to tackle our major fiscal and economic challenges.”

Standard & Poor’s cited “difficulties in bridging the gulf between political parties” as a major reason for the downgrade to AA+, the next level down from AAA. The rating agency has essentially lost faith in Washington’s ability to work together to address its debt.

The downgrade, hours after markets closed on Friday, is a first for the United States since it was granted an AAA rating in 1917. S&P warned about a downgrade as far back as April. Its decision came just four days after fractious debate over raising the nation’s debt ceiling ended in a compromise that would reduce the country’s debt by more than $2 trillion. S&P said Friday the cuts did not go far enough.

Both political parties used S&P’s report to buffet their policy cases and attack the other side.

House Speaker John Boehner, R-Ohio, said he hoped the downgrade served as a wake-up call to the Democratic Party.

“It is my hope this wake-up call will convince Washington Democrats that they can no longer afford to tinker around the edges of our long-term debt problem,” Boehner said in a statement. “As S&P noted, reforming and preserving our entitlement programs is the key to long-term fiscal sustainability.”

Senate Majority Leader Harry Reid, D-Nev., while not calling out Republicans by name, said S&P’s action showed that Democrats’ preferred policy approach — a mix of raising taxes and budget cuts — was the correct way to move forward.

“The action by S&P reaffirms the need for a balanced approach to deficit reduction that combines spending cuts with revenue-raising measures like closing taxpayer-funded giveaways to billionaires, oil companies and corporate jet owners,” Reid said.

At least one senator, Republican Mark Kirk of Illinois, called for the president to bring Congress back from its August recess to try and address the issues raised by S&P’s report.

The debt-limit deal called for a nearly $1 trillion down payment on deficit cutting, and instructed a special congressional committee to draw up a blueprint for another $1 trillion-plus by November.

Obama met with Treasury Secretary Timothy Geithner in the Oval Office late Friday afternoon before leaving for his weekend at Camp David.

S&P’s decision, though, clearly angered the Obama administration.

Officials at the Treasury Department fought the downgrade until virtually the last minute. Administration sources familiar with discussions said the S&P analysis was fundamentally flawed. They spoke on condition of anonymity because they weren’t authorized to discuss the matter publicly.

S&P had sent the administration a draft document in the early afternoon Friday and the administration, after examining the numbers, challenged the analysis.

In a statement, the Treasury Department said, “A judgment flawed by a $2 trillion error speaks for itself.”

Potential opponents of the president in 2012 pounced on S&P’s announcement.

Rep. Michele Bachmann, R-Minn., a tea party favorite, called on Obama to fire Geithner and quickly submit a plan to balance the budget, not just reduce deficits. Former Massachusetts Gov. Mitt Romney said the credit downgrade was the “latest casualty” in Obama’s failed economic leadership.

S&P said in its report that downgrading the U.S.’s credit rating reflected the agency’s belief that the debt deal Congress pulled together was not sufficient “to stabilize the government’s medium-term debt dynamics.” S&P said that in addition to the downgrade, it is issuing a negative outlook, meaning that there was a chance it will lower the rating further within the next two years.

A downgrade a notch lower, to AA, will occur if the agency sees smaller reductions in spending than Congress and the administration have agreed to make, higher interest rates or new fiscal pressures during this period.

At this point, the downgrade is a psychological blow to an economy that has struggled to recover from the financial tumult of 2008. Though widely predicted, S&P’s decision comes at a time when investors already appear spooked by U.S. economic indicators and debt troubles in Europe.