Washington DC - US lawmakers announced a bipartisan agreement Sunday on fiscal year 2024 funding totals that marks a step towards averting a looming government shutdown in a presidential election year.

The agreement on a roughly $1.6 trillion "topline" federal spending limit was announced by Republican House Speaker Mike Johnson and Democratic leaders in Congress after weeks of negotiations.

It was swiftly applauded by President Joe Biden, who said in a statement that the deal "moves us one step closer to preventing a needless government shutdown and protecting important national priorities."

But time is short for the rival parties in Congress to agree on the spending particulars and pass legislation before a January 19 deadline, when parts of the federal government would run out of funding.

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The deal, built on an agreement crafted last year by then House speaker Kevin McCarthy and the White House, reportedly includes an increase in Pentagon spending to some $886.3 billion, well over $100 billion beyond the non-military spending outlined by Democrats.

"By securing the $772.7 billion for non-defense discretionary funding, we can protect key domestic priorities like veterans benefits, health care and nutrition assistance from the draconian cuts sought by right-wing extremists," Senate Majority Leader Chuck Schumer and top House Democrat Hakeem Jeffries said in a joint statement.

The agreement "clears the way for Congress to act over the next few weeks in order to maintain important funding priorities for the American people and avoid a government shutdown," they said, adding they have "made clear to Speaker Mike Johnson that Democrats will not support including poison pill policy changes" in the spending measures.

Biden in his statement says the deal "rejects deep cuts to programs hardworking families count on, and provides a path to passing full-year funding bills that deliver for the American people and are free of any extreme policies."

But it is likely to anger the far-right flank of Johnson's Republican House caucus, many of whom have pressed for fiscal belt-tightening.

"Don't believe the spin," the conservative House Freedom Caucus said in a statement on X, the former Twitter.

"Once you break through the typical Washington math, the true total programmatic spending level is $1.658 trillion – not $1.59 trillion. This is total failure."

But in a letter to colleagues, Johnson reportedly highlighted conservative victories including a $10 billion downsize of the Internal Revenue Service budget and "real reductions" in the federal bureaucracy.