Advocates were urging young immigrants awarded three-year work permits with deferred deportation to return them to the federal government as the administration began on Thursday visiting homes of people who still have the permits.

“Our message to those who received their three-year work authorizations is, return them as soon as possible to avoid losing your DACA and falling out of immigration status,” said Cristina Jimenez, managing director of United We Dream.

The three-year permits were issued after President Barack Obama expanded the DACA program in an executive action. But then a Texas judge in February blocked the president’s action. The administration says some three-year work permits, those issued after Feb. 16, were issued by mistake after the judge issued a temporary injunction. The issue was brought to light amid the lawsuit filed by 26 states challenging Obama’s executive action.

Immigration advocates said in a statement they fear the visits will cause confusion and panic and so are working to inform the immigrant community.

The returned permits would be replaced with two-year permits.

Some 2,500 young immigrants who do not have legal status were given three-year permits to work when they were approved for deferred deportation this year under the Deferred Action for Childhood Arrivals (DACA) program or when their DACA was renewed.

About 1,000 of the 2,500 permits were returned and exchanged for two-year permits. Those who haven’t complied are being threatened with revocation of their DACA status. Some of the holders have failed to respond to letters and phone calls.

The home visits were to occur in Chicago, Los Angeles, Dallas and Houston, said Christopher Bentley, spokesman for Citizenship and Immigration Services, part of the Department of Homeland Security,.

Marielena Hincapié, executive director of the National Immigration Law Center, called the home visits by the federal immigration agency “extreme measures,” but urged holders of the documents to comply.

“While immigrant communities might be confused and fearful of this, (the) goal is only to retrieve the three-year work permit and replace it with a two-year permit,” Hincapié said.