The Obama Administration is urging dismissal of a lawsuit that threatens to dismantle the president's executive action on immigration reform.

The complaint filed by Arizona Maricopa County sheriff Joe Arpaio argues the program will serve as a magnet for more undocumented immigrants to come to the U.S. Ever controversial, Arpaio says the new arrivals will commit crimes and thus burden his law enforcement resources.

The Justice Department told the U.S. District Judge Beryl Howell in court filings on Monday that the case is "meritless."

Adding that "the sheriff's theory is speculative and unsubstantiated and that Arapio has failed to show he will suffer any injury at all from the federal government's program."

Arpaio's lawsuit was filed within hours of President Barack Obama's announced on immigration reform. He said in a statement at the time of filling, "I am not seeking to myself enforce the immigration laws as this is the province of the federal government. Rather, I am seeking to have the president and the other defendants obey the U.S. Constitution."

In the suit, he says Obama was "hijacking" previous immigration regulation by changing key terms to "create a radically new and different regime of immigration law and regulation."

President Obama's executive plan would in part offer deferred deportation for three years for parents of children who are either citizens or permanent residents and would offer parents temporary work papers. A more permanent solution would require Congressional input or an extension of the program by the next president.

Arpaio, in his sixth term as sheriff of Maricopa County, gained national fame for his controversial tactics in dealing with the flow of undocumented immigrants crossing the Arizona border from Mexico. These included demanding immigration papers during routine traffic stops.

Separately, 24 states have joined in a federal court challenge in Texas alleging that Obama violated constitutional limits on presidential power.