Fifteen Republican states on Monday night asked a federal judge to keep a Covid-era policy in place that allowed authorities to severely restrict asylum-seekers from crossing the border into the country after the judge issued a ruling last week that blocked the rule.

The GOP states said that lifting the rule, which the Biden admin straight has sought to end, will increase the flow of migrants and “directly harm” them.

“Because invalidation of the Title 42 Orders will directly harm the States, they now seek to intervene to offer a defense of the Title 42 policy so that its validity can be resolved on the merits, rather than through strategic surrender,” the states said in their filing Monday.

They argue that an increase in migrant flows to the border will “impose financial burdens on the states involuntarily hosting them” and that the states themselves are “entitled to special solitude in the standing analysis.”

“The States have sovereign and quasi-sovereign interests in controlling their borders, limiting the persons present within those borders, excluding persons carrying communicable diseases, and the enforcement of immigration law,” the filing said.

Last week, U.S. District Judge Emmet Sullivan vacated the controversial rule, known as Title 42, which U.S. Customs and Border Protection has used to turn back migrants at the border before they could make asylum claims. Sullivan sided with the American Civil Liberties Union and other immigration advocates, who argue that the rule was being used a tool to enforce the border more than a public health measure.

Sullivan cited the Administrative Procedures Act in his ruling, and characterized Title 42 as “arbitrary and capricious.” The Biden administration indicated that it won’t oppose Sullivan’s order in a court filing last week, but requested a temporary delay in lifting Title 42.

The Department of Homeland Security requested five weeks “to prepare to transition” to processing all migrants under pre-Covid policies, allowing them to cross the southern border to claim asylum. In his order, Sullivan granted the request with “great reluctance.” Title 42 is set to come to an end on Dec. 20, taking effect on midnight Dec. 21.

“To be clear…Title 42 would remain in place for some period. During the period of this freeze, we will prepare for an orderly transition to new policies at the border,” DHS said in a statement last week.