Senate Democrats privately debated how to respond to Majority Leader John Thune’s plan to push a vote on funding the Defense Department.

Some Democrats indicated they were ready to block a procedural motion on Thursday, but uncertainty about whether Thune will bring a standalone defense bill or combine it with other appropriations complicated their strategy.

Democrats are divided over whether supporting the defense bill could undermine leverage in ongoing shutdown negotiations, especially over health care.

Some worry voting against it would appear as opposing troops, while others want to focus on broader budget concessions, Axios has reported.

The situation highlights deep mistrust between Democrats and Republicans in the Senate.