WASHINGTON — A class-action lawsuit filed in federal court on Thursday alleges the Trump administration’s ban on legal immigration in response to the COVID-19 pandemic unfairly separates parents from children who are on the cusp of turning 21 years old.

One such parent named in the lawsuit, a Mexican woman filing under the name Mirna S., lives lawfully in the Bronx under a visa granted in exchange for her cooperation with U.S. law enforcement against her abusive ex-husband. She was due to bring her 20-year-old daughter safely to the U.S. in the coming months on an already-approved visa, but will now be unable to do so because her daughter will turn 21 in June.

President Donald Trump’s April 22 proclamation significantly curtailed legal immigration into the U.S., including limiting entry for immigrants’ children who are 21 and older. Advocates say they do not know how many people that specific provision may affect, but the Migration Policy Institute estimates that the proclamation as a whole will affect more than 50,000 over 60 days.

Those children are now put into a new non-prioritized category, where wait times for visas can take up to 76 years, the lawsuit alleges.

Although Mirna S.’s attorney made multiple requests to expedite her daughter’s visa application, the lawsuit alleges that the administration’s order was issued so quickly that “it was virtually impossible for any visa petitioner with a sponsored child … to seek emergency consular services before it took effect.”

“For the United States citizens and lawful permanent residents sponsoring children and derivative child relatives who will turn 21 during the Proclamation’s effective period, the Proclamation will result in a lifetime of family separation,” lawyers for the plaintiffs said in the filing.

Although the executive order was issued for 60 days, the administration can extend or expand it and has plans to do so, according to a current and former administration officials

Karen Tumlin, founder of the Justice Action Center, one of the legal groups representing three parents with 20-year-old children in the lawsuit, said the new restrictions on legal migration are likely to have a long life.

“Even though it is temporary, we know that [White House advisor] Stephen Miller has expressly said he intends to expand this policy. And we know that that’s going to simply mean that there will be more families intentionally kept apart,” Tumlin told NBC News.

Tumlin said the lawyers in the case plan to the U.S. District Court for the District of Columbia for a temporary restraining order on the visa restrictions.

A previous lawsuit challenging the ban was thrown out of the same court because the plaintiffs could not establish that they would be severely harmed within the order’s 60-day lifespan. Tumlin said she and lawyers from the American Immigration Law Association, the Innovation Law Lab and Mayer Brown have focused specifically on families with children who are about to turn 21 in hopes that they will be more successful at proving the harm caused by the proclamation.