A bipartisan group of lawmakers warned Thursday that the U.S. Postal Service “could cease to function by this summer” if it doesn’t receive immediate help.

“This is a national emergency. The negative effects of this crisis will be borne hardest by those in rural areas — where millions of Americans are currently sheltering in place and relying on the Postal Service to deliver essential supplies,” the leaders of the Postal Preservation Caucus wrote in a letter to congressional leadership.