WASHINGTON — Racing the clock, the White House sealed a New Year's Eve accord with Senate Republicans late Monday to neutralize across-the-board tax increases and spending cuts in government programs due to take effect at midnight, according to administration and Democratic officials.

Under the deal, taxes would remain steady for the middle class and rise at incomes over $400,000 for individuals and $450,000 for couples — levels higher than President Barack Obama had campaigned for in his successful drive for a second term in office.

Spending cuts totaling $24 billion over two months aimed at the Pentagon and domestic programs would be deferred. That would allow the White House and lawmakers time to regroup before plunging very quickly into a new round of budget brinkmanship certain to revolve around Republican calls to rein in the cost of Medicare and other government benefit programs.