WASHINGTON (AP) — Several conservative Senate Republicans have swung behind a bipartisan budget bill, apparently giving it enough momentum to win a pivotal test in the Senate over the passive resistance of top GOP leaders.

It'll take at least five Republicans to advance the measure Tuesday over a filibuster threshold demanded by GOP leaders. Announcements by Republicans Orrin Hatch, Johnny Isakson, Saxby Chambliss and others Monday that they would back that step appeared to seal enough GOP support to advance the measure.

The budget would ease some of the harshest cuts required under automatic spending curbs. It would replace $45 billion in scheduled cuts for the 2014 budget year, lifting agency budgets to a little more than $1 trillion and essentially freezing spending at those levels for 2015.