WATCH LIVE: White House press secretary Karoline Leavitt holds first news briefing

The White House is pausing federal grants and loans starting on Tuesday as President Donald Trump’s administration begins an across-the-board ideological review of its spending.

White House press secretary Karoline Leavitt is scheduled to hold a news briefing at 1 p.m. ET. Watch in the player above.

“We’ve never seen anything like this,” said Marcia Howard, executive director of Federal Funds Information for States, a nonprofit that analyzes the effect of federal actions on states. “It is unprecedented.”

Although the federal government has rescinded unspent funds in the past, it hasn’t normally halted grants on the front-end, she said. The grant pause is perhaps most similar to a federal government shutdown, when a congressional impasse on spending legislation delays federal payments for some state and local services.

“What we generally have observed with states under those circumstances is that a couple of weeks isn’t hugely disruptive,” Howard said.

States on average receive about 30% of their revenues from the federal government, according to Federal Funds Information for States. The largest grant program is Medicaid, which provides health care for lower-income children and adults. But it’s unclear whether the Trump administration’s pause will interrupt the flow of Medicaid reimbursement funds to states.