Senate Democratic Leader Chuck Schumer warned Thursday that Democrats are prepared to risk a government shutdown at the end of the month if Republicans do not accept demands to include key health care protections in any funding legislation.

Schumer said he and House Democratic Leader Hakeem Jeffries are united in opposing any spending bill that lacks provisions to protect Medicaid and commitments not to roll back Affordable Care Act-related subsidies, and that Republicans and President Donald Trump would be held responsible if they refuse to negotiate a bipartisan deal. "Things have changed," Schumer said in an interview with The Associated Press.

The threat comes as lawmakers face a Sept. 30 deadline to pass appropriations bills to keep much of the federal government operating. Republicans have discussed a short-term continuing resolution to push the deadline past the end of the month, but Schumer said Democrats will not support a stopgap that fails to include health care protections or a commitment from the White House not to rescind funds that Congress has approved.

Schumer cited recent Republican-backed legislative moves, including tax and spending measures enacted this summer that he said trimmed Medicaid and other programs, and the Trump administration's decision to unilaterally claw back $4.9 billion in congressionally approved foreign aid in August. "How do you pass an appropriations bill and let them undo it down the road?" he asked.

Republicans have pushed back, saying Democrats will be blamed if they vote against measures that keep the government open. Senate Majority Leader John Thune, R-S.D., has urged Schumer to present a specific health care proposal, including an extension of expanded premium tax credits for many people who buy insurance through the ACA, which are set to expire at the end of the year. Some Republicans have signaled willingness to extend those tax credits ahead of the expiration.

Democrats' demand that Republicans reverse Medicaid changes enacted in recent tax and spending legislation is less likely to be accepted, according to GOP officials who say undoing those provisions would be difficult. Schumer acknowledged the political and legislative difficulty of some requests but said Democrats were unified in their core demands, a sharp contrast with earlier this year when he voted with Republicans to keep the government open and faced fierce criticism from within his party.

In March, Schumer and several Senate Democrats voted for a short-term funding measure that House Democrats, led by Jeffries, opposed. That vote drew calls for Schumer's resignation from some activists. This time, Schumer said, the caucus is aligned with House Democrats. He said polling he presented to colleagues at a closed-door lunch showed most Americans would blame the president rather than Democrats for a shutdown.

Schumer argued a shutdown would not be the worst outcome after what he described as the administration's repeated attempts to challenge congressional authority. "It will get worse with or without it, because Trump is lawless," he said.

The showdown comes amid escalating partisan tensions in the Senate, where negotiations over confirmation procedures broke down for a second time Thursday and Republicans have moved to change rules to overcome Democratic objections. The intra-chamber friction has complicated the path to consensus on spending and other business.

If talks fail, Democrats face a difficult choice: back a Republican-led funding package without the protections they seek or let the government close with no clear exit plan. Schumer said he acted on principle in March and again intends to follow what he believes is the right course for his party. "I did what I thought was right" in March, he said, adding that the situation is now different.

With the end of the fiscal month approaching, lawmakers on both sides of the Capitol are weighing political risks and policy priorities. Negotiations over funding, health care protections and assurances against future executive rescissions will determine whether a temporary extension or a full-year agreement is possible before the Sept. 30 deadline.