WASHINGTON — The Senate on Friday struggled to pass a $1.1 trillion spending package notable for its expansive spending on military and disease fighting abroad, as well as its scaling back of financial and environmental regulations at home.

In a late-night twist that is emblematic of the dysfunction plaguing the 113th Congress, partisan maneuvering in the Senate disrupted what leaders on both sides had expected to be a relatively smooth path toward final passage. Though the spending deal is still almost sure to pass, the Senate did not reach an agreement late Friday. Lawmakers plan to reconvene on Saturday and work through the weekend if necessary.

On his way out of the Capitol, Senator Harry Reid of Nevada, the Democratic majority leader, was asked where infighting would ultimately lead: “It will lead to passing the omnibus,” he said, referring to the spending package.

As a precaution, the House also passed another short-term funding measure on Friday that would give the Senate until Wednesday evening to push through the bill.