President Donald Trump’ s administration has acknowledged mistakenly deporting a Maryland man with protected legal status to a notorious El Salvador prison, but is arguing against returning him to the United States because of his alleged gang ties and the U.

El Salvador’s government rebuffed a request Wednesday from Sen. Chris Van Hollen (D-Maryland) to free Kilmar Abrego García, whose case has become a flash point in the battle over President Donald Trump’s mass deportation campaign since the administration mistakenly deported him last month.

US Sen. Chris Van Hollen traveled to El Salvador Wednesday seeking to meet with government officials there about Kilmar Abrego Garcia, a man who had been living in his state until he was mistakenly deported by the Trump administration last month to a mega-prison in the Central American nation.