The Senate majority leader, Harry Reid of Nevada, said Thursday night that he was abandoning efforts to pass a $1.2 trillion spending measure to finance the government through Sept. 30 because Republicans would not support it.

Mr. Reid said he would work with the Republican leader, Mitch McConnell of Kentucky, on a stop-gap spending bill instead. Senate Republicans also said they would not support a House-passed temporary spending measure running through the end of the fiscal year on Sept. 30. Instead, they want to develop a separate measure running only through the early part of next year.

At that point, Republicans will control a majority in the House and six additional seats in the Senate, giving them greater leverage over any spending decisions.

Republicans had pledged to stop the spending measure, even though it included millions of dollars for projects that they had requested, and had even threatened to force the entire bill, which is more than 1,900 pages, to be read aloud on the Senate floor.

Mr. Reid in floor remarks on Thursday night said that he had spoken with Republican senators who had previously expressed a willingness to support the spending bill and concluded they would not vote for it.

“They’re not going to support this legislation,” Mr. Reid said. “We now have a simple choice. Are we going to help people in America?” He added, “The answer appear that it’s going to be no.”

Mr. McConnell, in floor remarks, praised the Appropriations Committee, of which he is a member, for its work on the spending bill that he defeated.