The across-the-board cuts are mandated by the Sequestration Transparency Act, part of a deal worked out to end last year's U.S. debt-ceiling crisis. A congressional Joint Select Committee on Deficit Reduction, known as the supercommittee, was required to identify about $1.2 trillion in cuts to reduce the federal deficit. If it failed, then Congress could increase the debt ceiling but $1.2 trillion -- but that would trigger the sequestrations at the center of Friday's report by the White House Office of Management and Budget.
Roughly half the automatic cuts are to come from defense spending.
"Under the assumptions required for this report about the level of discretionary appropriations for FY 2013 and without additional changes to direct spending, this report's calculations show a sequestration of 9.4 percent for defense function discretionary appropriations and 10 percent for defense funding direct spending," the OMB report said. "The corresponding sequestration percentages for the non-defense function would be a reduction of 8.2 percent for discretionary appropriations and 7.6 percent for direct spending."
The OMB report repeated the administration's insistence that President Barack Obama "stands ready to work with Congress" to find ways to avoid sequestration.
"The president has already presented two proposals for balanced and comprehensive budget reduction," the report said. "It is time for Congress to act."
The OMB said its estimates are preliminary, and the actual cuts -- if the sequestration were to occur -- would "differ based on changes in law and ongoing legal, budgetary and technical analysis. However, the report leaves no doubt that the sequestration would be deeply destructive to national security, domestic investments and core government functions."
The OMB said it would prepare to implement the sequestrations but would prefer to achieve "balanced deficit reduction."
An OMB official, speaking on background to reporters Friday, said the administration "does not support the indiscriminate cuts" detailed in the report and cuts "should never be implemented."
The official blamed "Republicans in Congress and Republicans more generally" for refusing to accept higher taxes as part of "a balanced approach to deficit reduction."
"As soon as the tough choices come to be made, Republicans want to back off from a deal that they made not only with the president but with each other," the official said.
The cuts amount to about $984 billion -- the difference between $1.2 trillion and the deficit-reduction amount the supercommittee enacted -- so defense and non-defense cuts would each be about $492 billion.
The U.S. House Friday passed a bipartisan spending bill that will fund the federal government for the next six months. The measure, approved Thursday by a 329-91 vote, will prevent a budget battle until after the election, ABC News said.
The U.S. Senate is expected to vote on the measure next week.