President Trump has said for weeks that the agreement he recently signed into law to set spending levels at agencies across government for fiscal 2018 provided far too much funding on the non-defense side of the ledger, and the White House is now considering its options to roll back some of those increases.

Trump, according to numerous reports, is working with Republican leadership in Congress to initiate a rescission process to walk back some of the spending boosts provided in the recent omnibus appropriations bill. The little-used procedure would require Trump to send to lawmakers a list of accounts and programs he felt Congress overfunded, giving Congress 45 days to act before the request expires and agencies must spend the money that lawmakers allocated. Once the bill has gone through committee or otherwise been discharged, it would face an expedited vote requiring a simple majority vote in both chambers of Congress.

“As a matter of national security I’ve signed the omnibus budget deal,” Trump said last month. “There are a lot of things that I’m unhappy about in this bill. There are a lot of things that we shouldn’t have had in this bill.”

Matt Sparks, a spokesman for House Majority Leader Kevin McCarthy, R-Calif., confirmed rescission is an issue the administration and Congress “are taking seriously and are currently engaged on.”

A rescission request would give Trump the ability to target exactly what he sees as problematic in the $1.3 trillion bill he signed into law. The procedure to revoke funds would require the White House to identify specific areas where the administration would need less money than Congress provided, rather than a broad, across-the-board type of cut.

The exact process by which Congress would go about voting on the bill remains unclear, as the steps outlined by the 1974 Congressional Budget and Impoundment Control Act have rarely been put into operation. The law clearly states the Senate would not be able to filibuster the bill itself, but may be able to require 60 votes on a motion to proceed. The Senate parliamentarian would likely have to issue a ruling on that point. Even if it can move forward with a simple majority, the Senate would require all of its current 50 members to approve the cuts, assuming Democrats vote en bloc against them. The Senate approved the omnibus by a 65-32 vote.

Congress tends to meet presidential requests to reduce funding allocations with skepticism, and according to 2009 Government Accountability Office testimony, it has approved just 39 percent of rescission proposals. Under President Clinton, the last administration to ask for a revocation of funds, lawmakers approved two-thirds of requests. Under President George H.W. Bush, Congress signed off on just 20 percent.

Marc Goldwein, senior policy director for the Committee for a Responsible Federal Budget, said “rescissions happen” but are much more common in the next year’s spending bill, supplemental appropriations or continuing resolutions, once agencies and lawmakers have the chance to evaluate their needs versus the amount they were previously allocated.

“To think that appropriators are going to be getting it exactly right throughout the year, a $1.3 trillion bill...I think is asking too much of them,” Goldwein said.

What is unusual in this case, however, is that agencies have not yet had the opportunity to evaluate the new funding level and its impact on their operations throughout the year. Goldwein said the details of the rescission request will demonstrate what is motivating the Trump administration. Appropriators may simply be attempting to fix mistakes included in a rushed spending package, he said, or Trump may be cynically attempting to eliminate funding he does not like.

GAO would play a key role if Congress rejects the rescission request and Trump decides to press forward with the cuts anyway. The 1974 law empowers Gene Dodaro, the head of GAO who was appointed by President Obama after being elected by a bipartisan, bicameral congressional commission, to sue the president for failing to spend money appropriated by Congress. Dodaro would have to send a letter to congressional leadership spelling out the necessity of the suit prior to bringing a civil case before the U.S. District Court for the District of Columbia to require the release of the funds. GAO has only filed such a suit once, leading to the president backing down and allowing the money to be spent.

Democrats were quick to meet the proposal with disapproval.

“The omnibus was a responsible agreement enacted into law with bipartisan votes and the president’s signature,” said Matt Dennis, a spokesman for Democrats on the House Appropriations Committee. “Calling for a do-over because you didn’t like the press coverage after the fact is the height of absurdity.”

A spokeswoman for Republican appropriators said she had no comment on the rescission plan as the committee has not yet received any request from the White House.

Goldwein said some lawmakers, especially in an election year, may decide that voting for rescission would be a good message that they are standing against wasteful spending right after they voted for a budget deal that raised caps by $150 billion. Others, he suggested, will not want to refocus on an issue they thought was already behind them and they can let disappear simply by taking no action.