Shortly after President Barack Obama announced his immigration reform Thursday night, an Arizona Sheriff filed a lawsuit against the president, claiming that his executive action is unconstitutional.

Maricopa County Sheriff Joe Arpaio, "America's Toughest Sheriff," as he calls himself, said that in bypassing Congress to unilaterally and temporarily grant immunity to millions of illegal immigrants, Obama acted outside of the framework allowed by the constitution, reported Reuters.

"He speaks a good game - and I understand where he's coming from in way - on the other hand, let's not con the American public. How are we gonna keep track of these 5 million people?" Arpaio told KNXV-TV.

In Obama's address, he announced that 4.7 illegal immigrants in the U.S. will now be eligible for temporary protection from deportation and will also be able to obtain work permits. To do so, immigrants are required to pass a criminal background check and pay taxes.

The lawsuit claims Obama's actions effectively granted amnesty to the undocumented immigrants, and would work to encourage more illegal border crossing. Arpaio told KNXV-TV that his lawsuit will try to block the executive order on the grounds that it is unconstitutional, adding that his lawyer will not be paid using taxpayer money.

"This is going to open the door. Everybody in Mexico, Central America, thinks they will have a free pass when they come into our country because of what the president is issuing," said Arpaio.

"[Obama's immigration] programs are unconstitutional abuses of the President's role in our nation's constitutional architecture and exceed the powers of the President within the U.S. Constitution," Arpaio's complaint read, which was filed in a federal court in Washington.

During Obama's Thursday night prime-time speech detailing his immigration plan, he refuted claims that his executive action amounted to amnesty.

"Amnesty is the immigration system we have today, millions of people who live here without paying their taxes or playing by the rules," Obama said.