House Majority Leader Kevin McCarthy (R-Calif.) on Capitol Hill last month. (Chip Somodevilla/Getty Images)

The White House is eyeing a long-shot plan to slash spending from the $1.3 trillion budget bill signed reluctantly by President Trump late last month.

A spokesman for House Majority Leader Kevin McCarthy (R-Calif.) confirmed Monday that McCarthy’s office is working with the Trump administration on the approach, which would evidently rely on an obscure 1974 law that allows presidents to try to cancel spending authority already approved by Congress.

The spokesman, Matt Sparks, said planning was in the early stages and there were no details.

White House legislative director Marc Short said Monday, “The administration is certainly looking at a rescission package, and the president takes seriously his promise to be fiscally responsible.”

It is expected that the White House would send a request for the “rescission” to Capitol Hill once Congress returns from its spring recess next week. However, Congress would need to approve the request, making it a long shot given all-but-certain Democratic opposition.

The White House move would follow widespread conservative criticism of the “omnibus” budget bill, which increased spending by tens of billions of dollars for the military and domestic agencies while not including much money for Trump’s border wall.

House Freedom Caucus Chairman Mark Meadows (R-N.C.), an outspoken critic of the ballooning domestic spending in the omnibus, praised McCarthy for working with the White House on a plan to pare it back. Meadows said he was “very supportive and extremely pleased with the leadership’s willingness to engage on the issue. Leader McCarthy heard from constituents and worked quickly to address the issue in a meaningful way.”

Trump threatened to veto the $1.3 trillion spending bill before ultimately signing it, but in the course of doing so he demanded a line-item veto, which has been ruled unconstitutional by the Supreme Court.

“Rescission authority” is a related mechanism that allows presidents to submit to Congress a request to cancel spending it has already approved. Under the Impoundment Control Act of 1974, Congress has 45 workdays to approve the rescission request, according to the Congressional Research Service. If Congress does not act, the money is made available.

Despite support from conservatives for a White House attempt to reduce domestic spending it deems unnecessary, any such plan would have trouble getting through the Senate, where the GOP holds a slim 51-to-49 majority, and even some Republicans might be reluctant to go along.

The plan was first reported by ABC News.