WASHINGTON—Senate Republicans have killed a plan backed by President Barack Obama to replace $111 billion in government spending cuts this year with a new minimum tax on the wealthy and cuts to defense and farm subsidies that would be slower to strike.

The plan received a 51-49 majority vote but failed in the Senate because 60 votes are required to overcome a GOP-led filibuster.

Republicans object to $55 billion worth of new taxes and urge an alternative that would give Obama greater flexibility to deal with the automatic cuts.

The vote comes just a day before the automatic cuts are set to start to take place, yet there was never any hope that the Democratic measure would have passed because it was crafted without GOP input.