President Trump is putting forward a nominee who is virulently anti-immigrant to be assistant secretary of state for the Bureau of Population, Refugees and Migration, a job I used to hold in the Obama administration. The nomination, announced last week, is only the latest move by the administration to chip away at our standing as the world’s top backer of humanitarian efforts.

The new nominee, Ronald Mortensen, has made his positions on immigration issues clear as a fellow of the Center for Immigration Studies. For example, he has insisted that most of the Dreamers — undocumented immigrants brought to the United States as children — have committed felonies. But his likely hostility to the mission of the bureau is not unique: the administration has named several immigration hard-liners to key posts. Rather, Mr. Mortensen’s nomination needs to be understood as part of a campaign to change America’s long tradition of welcoming refugees and immigrants and offering sanctuary to the persecuted.

President Trump’s anti-Muslim travel ban, announced shortly after his inauguration, was the first salvo in this campaign. Even with courts overturning various versions of the ban, the White House has succeeded in slashing the number of refugees admitted to the United States to the lowest level in years — from 85,000 in the last full year of the Obama administration to as few as 20,000 projected for this year.

The network of faith-based and secular charities around the United States that support refugee families to create new lives is disintegrating. With so few refugees being admitted, the State Department has announced plans to no longer fund some of these groups. The result is that fewer cities will be involved in the resettlement programs, the staff and volunteers who help refugees will disperse, and we will lose part of a highly successful public-private partnership. Lost, too, will be the proven economic and cultural benefits additional refugees would bring and the chance for a fresh start they desperately need.