Senators in both parties say the odds are rising of another government shutdown in September after President Trump demanded that GOP leaders abolish the filibuster or face a spending showdown and another shutdown.

Trump blindsided GOP leaders on Monday when he warned there could be another shutdown if Senate Republicans don’t abolish the filibuster, which would allow them to pass the Safeguard American Voter Eligibility (SAVE America) Act and spending legislation without any Democratic votes.

GOP senators have made it clear they don’t want to risk a shutdown before the November elections, but Trump is bracing for another battle with Democrats that could shutter federal departments and agencies.

Trump warned that unless Republicans abolish the filibuster, another shutdown is likely.

“It’s so important that Republicans have to do it. It’s so insane. Otherwise, we’re going to have a shutdown in September,” Trump said of his desire to abolish the Senate filibuster during a “Fox & Friends” interview Monday.

Senate Democratic Leader Chuck Schumer (N.Y.) said Trump’s comments show that the president is getting ready to shut down federal agencies for the third time in the past year because he refuses to negotiate with them on increasing funding for Democratic priorities.

“Donald Trump’s the mastermind at making things worse and worse and worse,” Schumer said Monday on the Senate floor. “Donald Trump told ‘Fox & Friends’: ‘Republicans have to terminate the filibuster. It’s so insane. Otherwise, we’re going to have a shutdown in September.’”

“The Trump shutdown, he’s bragging about it. He’s predicting it. ‘Republicans have to terminate the filibuster, or we will have a shutdown in September,’ says Donald Trump,” Schumer added.

Those comments caught Senate Majority Leader John Thune (R-S.D.) off guard.

“Shut down the government if we don’t abolish the filibuster? A new line,” he said.

Senate Democrats think it’s increasingly likely that Trump may refuse to sign into law a short-term government funding package if Republicans don’t pair it with the SAVE America Act, which would require people to prove citizenship when registering to vote, show photo identification at the polls and restrict mail-in ballots.

“This president wants to shut down this government. It shows his chaos, his continuing corruption and not being about serving the American people. He should not be shutting down the government,” said Sen. Cory Booker (D-N.J.).

A Democratic senator who requested anonymity said both sides are “testing the waters” ahead of another possible government shutdown, trying to assess which side would get more of the blame a few weeks before the Nov. 3 midterm election.

“We don’t think Thune has any interest in a shutdown,” the Democratic senator said.

But the lawmaker said Trump may provoke a fight with Congress over the SAVE America Act that could trigger a shutdown.

“If Trump says, ‘I’m shutting it down if you don’t pass the SAVE America Act,’ go right ahead. You’re driving the Republican train right over the cliff, and you just keep driving it. If there’s a shutdown, they’ll own it. There are members on the Republican side who think that’s crazy,” the Democratic senator said.

Republicans say they’re worried about Democrats shutting down government in the fall to protest the military conflict with Iran or to extract concessions from the Trump administration.

“We’ve continued to push our Democratic colleagues, saying, ‘If you guys are going to shut down the government, we ought to know about it in advance,’” Sen. Mike Rounds (R-S.D.) said.

Rounds said that while many rank-and-file Democratic senators want to avoid another shutdown, the Democratic leadership appears to be gearing up for another battle with Trump that could leave hundreds of thousands of federal workers furloughed.

“Most of the folks that we talk with — I believe them when they say that they do not intend to shut down government, but apparently their leadership has a different point of view. That’s where I think the problem is right now,” Rounds said.

“Democrats should want to find a path forward on bipartisan appropriations,” he added.

Democrats fired a warning shot at Republicans on Tuesday by voting along party lines to block the $1.15 trillion annual National Defense Authorization Act (NDAA), which usually passes the Senate with strong bipartisan support.

The bill advanced out of the Senate Armed Services Committee last month with Democratic support, but the partisan battle lines are hardening as the midterm elections approach.

Senate Armed Services Committee Chair Roger Wicker (R-Miss.) called the Democratic blockade a bad sign for the coming government funding fight.

“It’s unprecedented to not pass the motion to proceed to the NDAA, and it reflects a decision and a mindset on the part of Sen. Schumer not to cooperate because so much of this has been done on a bipartisan basis,” he said. “It really is a new low.”

Senate Appropriations Committee Chair Susan Collins (R-Maine) urged both sides to step back from the brink.

“A shutdown is always bad, always. It represents an ultimate failure to govern, and I hope that the Democrats will not repeat the tactics that led to shutdowns last year,” she said.

Schumer accused Republicans of pushing “lopsided” spending bills that substantially increase defense funding levels while leaving nondefense programs with paltry increases.

“There is nothing normal about manufacturing a partisan process and then accusing Democrats of wanting a shutdown because we refuse to rubber-stamp the result. Fighting for a budget that delivers for the American people is not weaponization. It is our job,” he wrote in a “Dear Colleague” letter Monday.

Republicans are discussing strategies to pass legislation that would blunt the impact of a shutdown.

One proposal, the Shutdown Fairness Act, sponsored by Sens. Ron Johnson (R-Wis.) and Todd Young (R-Ind.), would ensure that federal workers are paid during a government funding lapse.

“The one good idea that’s come out of all this is a bill that Ron Johnson’s put forward to pay the government employees when there’s a disagreement over spending,” Sen. Rand Paul (R-Ky.) said. “I hope there’s not another shutdown, but if the Democrats decide to do it, I think we should try to bring that bill up.”

Passing that bill, however, would likely require moving it through the budget reconciliation process to shield it from a Democratic filibuster and getting the green light from the Senate parliamentarian to pass it through the Senate with a simple majority.