President Donald Trump has complained vigorously about wasteful federal spending. With a message to Congress on May 8, he will seek to do something about it with a historically large rescission proposal.

The message will be under the auspices of the Congressional Budget and Impoundment Control Act of 1974, which provides for a process for a president to request that Congress remove the authority for specific, previously granted funding. Such a denial of funding is called a rescission.

According to a senior administration official, presidents from Gerald Ford on, with the exceptions of George W. Bush and Barack Obama, have used rescissions to reduce federal spending. The $15 billion to be proposed by Trump is the largest single rescission request made by any president.

The official said this is the first of several such requests, and it has been tailored to attract the largest possible Congressional support.

The official quoted minority whip Steny Hoyer (D-Md.) as saying: “I wouldn’t irrationally oppose a rescission which said we’ve had money laying in an account that has not been spent for one, two, or three years. It shouldn’t have it just sitting in that account.”

In line with Hoyer’s comment, the administration’s focus in this proposal is on unobligated balances. In layman’s terms, they are proposing to clean up funding that no longer has any purpose or legal authority.

For instance, $4.3 billion is budgeted for the Advanced Technology Vehicle Loan program, which has not made a loan since 2011.

$800 million is budgeted for the Center for Medicare and Medicaid Innovation, which, the official said, will not be able to spend the money before 2020, when the Center receives another $10 billion under the terms of Obamacare.

The legal authority for one program with money on the books expired in 2012; another was funded to address disease outbreaks that have since been resolved; money budgeted for protecting the Hurricane Sandy emergency watershed program has not been spent because local governments have not been able to provide matching funds. And so these are on the chopping block.

One of the most eye-catching proposals is to rescind $7 billion from the Children’s Health Insurance Program. The official said the legal authority for $5 billion had lapsed. And the other $2 billion was for a contingency program for states that, the official said, no state would qualify for.

Once President Trump’s message is transmitted to Congress, a 45-day period begins in which the accounts named are frozen.

Those 45 days give Congress a chance to act. A bill is introduced that can be passed by a simple majority. No filibuster in the Senate is allowed. Congress can remove items from the president’s request, but can’t add items to it. If Congress does not pass a bill, the president’s request is void.

The official said House members are enthusiastic about the president’s proposal, and the administration has ongoing discussions with Senate leadership.

While removing such budgetary deadwood as addressed in this proposal would seem to be completely uncontroversial, such unobligated balances have their purposes in the complexities of Congressional budgeting. They can be used as “pay fors” for more spending. By cutting this useless spending, one can raise newspending a corresponding amount, without the budget on paper increasing. And so profligate spenders may not line up to support this rescission request.

The official emphasized that the administration wanted with the current proposal to get process of rescission back in the “muscle memory” of official Washington so that future efforts will become more routine.

Other rescission proposals will be introduced once this one is resolved. At least one will look to rescind spending from the just passed omnibus spending bill, the likes of which Trump said he would never again sign, so out of control was its spending.

Another proposal will likely address $178 billion in duplicative spending identified in the Government Accountability Office.