The Senate may end a filibuster by invoking cloture. Senate Republicans invoked the "nuclear option" after the April6 filibuster that prevented cloture. The debate was filibustered, with a motion of cloture falling four votes short. Senator Inouye voted against invoking cloture, and Senator Salazar did not vote. The bill failed a cloture vote. But the Senate voted for cloture and passed the bill. The Senate voted on eight cloture motions in December. Six Republicans voted with a majority of Democrats against cloture in the Senate. Brown was one of five Republican senators to vote for cloture on the jobs bill. The bill failed to pass a cloture vote, essentially killing it. From 1917 to 1949, the requirement for cloture was two-thirds of senators voting. In the US Senate, there are no formal rules against dilatory tactics except under cloture. Nelson was the 60th and last senator to agree to vote for cloture. On June 20, 2005, the Senate voted again on cloture. The vote on the cloture motion had been scheduled for May 21, 2012.