President Donald Trump’s budget director has talked about attempting the ultimate override of Congress’ funding prerogatives during the final 45 days of the fiscal year — and that time is now.

With six weeks left until Oct. 1, lawmakers are staring down a government shutdown deadline alongside the threat of a “pocket rescission,” a controversial White House tactic to cancel federal cash without the consent of Congress. It’s also a ploy that the government’s top watchdog, along with key lawmakers from both parties, say is illegal.

“The money evaporates at the end of the fiscal year,” White House budget chief Russ Vought said last month in defense of the gambit, adding it has “been used before.”

Lawmakers anticipate Trump will send Congress a formal rescissions request to claw back billions of dollars in federal funding as soon as lawmakers return from recess in September.

Already, the threat of the White House then unilaterally canceling the funding in October — regardless of Congress’ response to the request — is straining negotiations between Democrats and Republicans desperately trying to head off a shutdown with bipartisan negotiations, which Vought is also actively seeking to undermine.

“He is trying to throw a wrench in this by introducing or sending to us a second rescission bill — by trying to do pocket rescissions,” Delaware Sen. Chris Coons, the top Democrat on the appropriations panel that funds the military, said of Vought in an interview.

It also would undoubtedly throw Republicans into another politically dicey balancing act of trying not to buck their president while answering to constituents who are feeling the effects of the administration’s mass gutting of widely used government programs.

Congress cleared an initial rescissions package of $9 billion in cuts to public broadcasting and foreign aid in July. The White House has stayed publicly mum on what sort of programming it would seek to slash next, but officials have previously signaled the Department of Education will be the target of a second package, which could align with Trump’s controversial goal of eventually eliminating the agency altogether.

As for the size of this upcoming clawbacks request, Republicans have mixed predictions. Last month, Speaker Mike Johnson told members that a second package would be less than the $9 billion, but other GOP lawmakers said they expect to be asked to revoke much more money than that.

Under decades-old budget law, the White House is allowed to send Congress a rescissions request and then withhold the cash for 45 days while lawmakers consider whether to approve, reject or ignore the proposal. If lawmakers don’t pass the rescissions bill, the administration must spend the money as Congress intended. These were the conditions under which the administration transmitted its most recent plan.

Now, with less than 45 days before the current fiscal year comes to a close, top Trump administration officials argue the White House can send another rescissions package and then treat the funding as expired come midnight on Sept. 30 — regardless of congressional action.

And if the White House moves forward with the plan, it could do more than just cause political headaches. It very likely would kick off a high-stakes legal battle over Congress’ funding power and whether a presidential administration must spend all of the money prescribed by law or whether the spending levels are simply “a ceiling,” as Vought has contended.

The Government Accountability Office has said repeatedly that pocket rescissions are against the law and would “cede Congress’s power of the purse by allowing a president to, in effect, change the law by shortening the period of availability for fixed-period funds.”

Vought has taken aim at the watchdog, and Mark Paoletta, the Office of Management and Budget general counsel, piled on this month.

“Trump Derangement Syndrome is on full display” at GAO, Paoletta said on social media, and “wrong on pocket rescissions.”

“Congress is well aware” that the law allows the maneuver, he added, pointing out that lawmakers did not bother heeding GAO’s urging 50 years ago to fix a loophole leaving the legality question open to interpretation.

Yet even some of the Republican lawmakers who are hungry for more chances to kill funding are wary of the Trump administration using the rescissions process to undermine Congress’ funding power under Article I of the Constitution.

Sen. Thom Tillis (R-N.C.), who reluctantly voted in support of the rescissions request last month, said he won’t support more clawback packages if the White House doesn’t provide account-by-account details of how the funding would be cut.

“I’m just not going to aid and abet moving appropriations decisions over to the Article II branch,” Tillis said in an interview.

Trump “just happens to be a Republican,” Tillis continued, but “we could regret this, just as Democrats would, if they are tempted to do the same thing. That’s why you’ve got to draw lines here institutionally.”

Concerns about precedent, legality and political appetite are converging on the reality for members of both parties that Republicans can’t afford to alienate Democrats, whose votes they likely need to pass any government funding bill to avoid a shutdown next month.

Senate Majority Leader John Thune, when asked about a second rescissions package, stressed he would prefer to handle any more cuts through the regular appropriations process. “My hope would be that that’s the way we deal with a lot of these issues,” he said.

Democrats hope so too, and they have warned that any Trump administration effort to claw back money already approved by Congress — “pocket” or otherwise — would undermine lawmakers’ ability to work across party lines to avoid a shutdown.

In remarks late last month alongside House Minority Leader Hakeem Jeffries and his party’s senior appropriators, Senate Minority Leader Chuck Schumer said Democrats would try to reach a compromise with Republicans despite GOP lawmakers’ approval of the latest $9 billion rescissions package.

But, he added, “Republicans are making it extremely difficult to do that … by talking about rescissions, pocket rescissions, impoundment — which would undo anything that we did in the budgets.”