President Trump plans to announce that his administration will temporarily bar family members of U.S. citizens and foreign workers looking to move to the U.S. in the next 60 days under a new executive order, according to an administration official.

The immigration suspension, which will affect tens of thousands of people, was first announced by Mr. Trump in a Monday night tweet in which he said it was designed to stem the flow of immigration at a time when tens of millions of Americans have lost jobs as a result of the coronavirus pandemic.

The order won’t block foreigners coming to the U.S. on temporary visas for work or travel. That category includes H-1B visas, which allow more than 85,000 high-skilled foreigners to come to the U.S. for at least three years to work. It also includes seasonal migrant workers who come to the U.S. annually to work on farms and at other businesses such as resorts or county fairs.