Sixteen Republican-led states including Texas have filed a lawsuit against President Joe Biden administration to stop a new programme that will allow hundreds of thousands of undocumented immigrants married to U.S. citizens to gain legal status.

In the suit filed before the U.S. District Court for the Eastern District of Texas on Friday, days after the programme opened for applications, the 16-Republican-led states are seeking a temporary restraining order and preliminary injunction to immediately suspend the programme, the New York Times reported.

The 16 states argued in their court filing that the programme was illegal given that it exceeded the discretion that the executive branch had to set policy.

“The Biden-Harris Administration — dissatisfied with the system Congress created, and for blatant political purposes — has yet again attempted to create its own immigration system,” the 67-page court filing said.

“This agency action is nothing less than mass amnesty cloaked in purported executive discretion — a sweeping, last-minute ploy by an administration bent on rewriting immigration laws without Congress,” it said.

Over 500,000 undocumented spouses of American citizens would be able to avoid deportation, granted pathway to citizenship and permission to legally work in the U.S. under the new policy, which the pursuant states said violates the law because it misused so-called parole.

The parole is an authority exercised by the Homeland Security Department to allow people outside the United States to enter the country for urgent humanitarian reasons, on a case-by-case basis.

“Republican elected officials continue to demonstrate that they are more focused on playing politics than helping American families or fixing our broken immigration system,” a White House spokesman, Angelo Fernández Hernández, said in a statement.

“The lawsuit aims to separate American citizens from their spouses and stepchildren who are already eligible for lawful permanent residency and could remain together through this process,” he added.

Meanwhile, the agency in charge of the programme, the Homeland Security Department, said it would defend the programme in court and continue to process new applications.