The Senate on Thursday rejected competing proposals to boost funding for defense and domestic programs, likely making it easier to soon pass its annual defense policy bill but setting up tough negotiations with the House.

The amendment face off was a partisan tit-for-tat that started with Armed Services Chair John McCain (R-Ariz.) introducing a proposal to raise defense spending by $18 billion by tapping a war funding account.

Democrats countered with their own proposal, drafted by Armed Services ranking member Jack Reed (D-R.I.), to spend $18 billion on domestic programs — also by using funds normally dedicated for military operations in Afghanistan and against the Islamic State.

On Thursday, both amendments failed in procedural votes that had a 60-vote threshold. McCain’s proposal went down on a 56 to 42 vote and Reed’s failed on a 43 to 55 vote. But in a twist, the votes did not break along party lines.

Thirteen Democrats broke with party leaders to support McCain’s bid to add more money to defense programs using war funds — more than enough to help Republicans carry the amendment, had the GOP stuck together. But ten Republicans voted against McCain’s measure, including the chairs of the Senate Appropriations, Budget, and Foreign Relations Committees, as well as Illinois Republican Sen. Mark Kirk, who is facing a tough reelection contest.

Two other vulnerable Republicans, Sens. Kelly Ayotte of New Hampshire and Rob Portman of Ohio, voted for Reed’s bid to raise domestic spending, while three Democrats voted against it.

The votes ensure that the Senate defense bill will keep spending levels in line with the 2015 budget deal that eased federal spending caps for a period of two years. About $80 billion in relief was divided equally across defense and domestic programs.

But last month, the House approved a defense bill that added $18 billion in funding for the Pentagon by tapping a war funding account, which allowed Republicans to skirt budget caps, despite the objections of many Democrats that raising defense spending alone would undermine the 2015 agreement.

Senate Democrats emphasized these concerns this week, arguing their proposed spending boost was necessary to maintain the parity between defense and domestic spending or else “the appropriations process will come to a grinding halt,” Sen. Charles E. Schumer (D-N.Y.) told reporters this week.

“Treating defense and non-defense equitably and fairly” was the central tenet of the 2015 budget deal, Sen. Patty Murray (D-Wash.) argued on the floor Wednesday, adding that it “is a principle we need to stick to if we want that good work to continue.”

Democrats and Republicans have long sparred over GOP-spearheaded proposals to increase the defense budget using war funds as a way of getting around statutory limitations on spending.

Last year, President Obama vetoed the defense bill over objections that it dipped too deeply into war funds to cover programs in the Pentagon’s budget, forcing negotiators back to the drawing table to come up with a plan that hewed more closely to budget numbers both parties could agree on.

Though the House GOP waded back into the war funds fight with its defense bill this year, McCain steered relatively clear, sticking to the agreed-upon numbers in the Senate’s defense bill that he drafted and that his panel approved last month. He saved the war funds fight for the Senate floor with his amendment.

Senate Democrats wanted to use the $18 billion in domestic spending for a variety of hot-button issues, such as funding for combating the Zika virus, recovery from lead-tainted water in Flint, Mich., and addressing the opioid crisis. They say they would support McCain’s new funding only if Republicans backed their plan.

The White House already objected to the House GOP’s effort to use an extra $18 billion of war funds for defense spending. On Tuesday, the White House also threatened to veto the Senate bill over a variety of issues.

Correction: An earlier version of the article misstated South Carolina Republican Sen. Lindsey Graham’s vote on the McCain amendment.