The Biden administration will keep using a public health rule to turn away migrants.

Politics|The Biden administration will keep using a public health rule to turn away migrants.

With the number of migrants crossing the southern border surging and the pandemic proving to be far from over, the Biden administration has decided to leave in place for now the public health rule that has allowed it to turn away hundreds of thousands of migrants, officials said.

The decision, confirmed by the Centers for Disease Control and Prevention on Monday, amounted to a shift by the administration, which had been working on plans to begin lifting the rule this summer, more than a year after it was imposed by the Trump administration. The C.D.C. said allowing noncitizens to come over the border from either Mexico or Canada “creates a serious danger” of further spread of the coronavirus.

President Biden has come under intense pressure for months from some Democrats and supporters of more liberal immigration policies to lift the rule, which critics say has been employed less to protect public health than as a politically defensible way to limit immigration.

The recent spread of the highly transmissible Delta variant has bolstered the argument that the public health rule, known as Title 42, remains necessary to contain the coronavirus. And the virus’s quickening spread comes as border officials are so overwhelmed with the persistent pace of illegal migration that they say that allowing more migrants into the country by lifting the rule poses the threat of a humanitarian crisis.

On Monday, the American Civil Liberties Union said it would move forward with a lawsuit seeking to force the administration to lift the public health order for migrant families after months of negotiations with the “ultimate goal” of ending the policy, one of the group’s lawyers said.

“It is now clear that there is no immediate plan to do that,” Lee Gelernt of the A.C.L.U., the lead lawyer on the case, said in a statement on Monday. “The administration made repeated public statements that it just needed some time to build back the asylum system the Trump administration depleted. We gave them seven months. Time is up.”

While the administration has used the rule to rapidly turn around single adults and many migrant families, it has not applied the restriction to migrant children arriving alone at the southern border, in a departure from the Trump administration.