Two competing bills aimed at averting huge spending cuts failed Thursday in the US Senate, including a Republican effort that would have ceded authority to the White House to implement the reductions.

Both bills fell short of the 60 votes needed to advance, virtually assuring that the $85 billion in indiscriminate, across-the-board cuts known as the sequester will kick in after the Friday deadline

With Democratic and Republican leaders opposed to each other's plans there was little chance from the start that either bill would pass the Senate.

Democrats want to raise new revenue by closing tax loopholes for the rich -- to replace about half the mandated cuts -- accompanied by targeted reductions.

The Republican plan would seek no new tax revenue, but would give President Barack Obama broad "flexibility" to determine where the budget ax would fall within different agencies of the government.

Democrats accused Republicans of sitting on their hands in the hopes that the spending cuts actually kick in.

Democratic Senator Chuck Schumer said Republicans were "dancing in the streets, happy with the thought that sequestration will happen."

Attention now turns to the Friday meeting that Obama has called with congressional leaders, and to next month's negotiations over funding for government operations for fiscal year 2013.

Despite the foregone conclusion of the votes, Republican Senator Chuck Grassley expressed his frustration at the chamber's inability to avert a crisis long in the making.

"You could have predicted this cliff 18 months ago," he told AFP. "You wait until the last day to bring things up over here? Where does the fault lie?"

Republican House Speaker John Boehner called the Senate performance "embarrassing."

"Now that today's political stunt to raise taxes has failed, it's time for the president and Senate Democrats to do the hard work that is necessary to pass a bill in the Senate so we can begin to resolve this issue."

The sequester was baked into law in 2011, when the White House and Republican leaders agreed on wide-ranging cuts designed to be so painful that they would force lawmakers to reach a more palatable compromise to rein in the massive debt.