A major conservative-libertarian advocacy group has thrown its support behind President Donald Trump’s call for canceling more than $15 billion in spending as a good first step in reining in the federal budget.

Americans for Prosperity praises the president’s rescission request, which would claw back up to $15.3 billion in appropriated but unspent funds, and says it will wage a media campaign to push for Congress to approve the request.

The group launched its “Stop Overspending” campaign over the Memorial Day weekend with the aim of encouraging lawmakers to curb excessive government spending through targeted efforts in congressional districts to educate voters about the issue.

“Every lawmaker who supports fiscal responsibility should embrace this opportunity to rein in spending,” Bill Riggs, spokesman for Americans for Prosperity, said in a statement. “This rescission package isn’t going to solve Washington’s spending problem, but it’s a commonsense first step to earning back the trust of taxpayers.”

“Overspending in Washington is a bipartisan problem, and it’s time members of both parties came together to start fixing it,” Riggs said.

Trump’s rescission request is the first of its kind since fiscal year 2000.

A rescission provides the president with the opportunity to save appropriated but unspent funds through a request to Congress. The funds are “locked up” and cannot be spent unless Congress rejects the proposal.

Americans for Prosperity called Trump’s initial rescission proposal an “opportunity for lawmakers to demonstrate fiscal responsibility by supporting this modest attempt to undo some of the overspending damage.”

The advocacy group acknowledged what it called the “significant achievement” for American workers of last year’s passage of the Tax Cuts and Jobs Act, but noted that the group long has campaigned for pairing tax cuts with spending restraint.

“Unchecked spending in Washington threatens to undermine economic growth,” the group said.

Justin Bogie, a senior fiscal policy analyst at The Heritage Foundation, said that passing Trump’s rescission request “would be a first step toward returning to fiscal sanity.” But, he noted, the measure is “not the long-term solution to the nation’s growing debt problem.”

“[It] is a powerful tool towards reining in wasteful spending,” Bogie said. “Congress should pass the current rescission request and then work with the president on subsequent packages targeting spending increases included in the latest budget deal.”