White House acting chief of staff Mick Mulvaney has pressed agency leaders to provide him with a list of the highest-impact programs that will be jeopardized if the shutdown continues into March and April, people familiar with the directive said.

Mulvaney wants the list no later than Friday, these people said, and it’s the firmest evidence to date that the White House is preparing for a lengthy funding lapse that could have snowballing consequences for the economy and government services.

The request is the first known inquiry from a top White House official seeking information about the spreading impact of the shutdown, which has entered its fifth week and is the longest in U.S. history. So far, top White House officials have been particularly focused on lengthening wait times at airport security, but not the sprawling interruption of programs elsewhere in the government.

The people spoke on the condition of anonymity because they were not authorized to disclose Mulvaney’s demand.