PHOENIX, Ariz. (CBSDC/AP) — Maricopa County Sheriff Joe Arpaio announced Thursday evening that he is filing a lawsuit against President Barack Obama for the executive action he is taking on immigration.

Arpaio told KNXV-TV that the president is conning the American public with his immigration plan.

“He speaks a good game and I understand where he’s coming from in a way. On the other hand, let’s not con the American public. How are we going to keep track of these 5 million people?” Arpaio said.

In an address to the nation, Obama announced that his executive actions are designed to make nearly 5 million immigrants illegally in the United States eligible for protection from deportation and for work permits. It would mainly cover parents of U.S. citizens and of legal residents as long as the parents have been in the U.S. for five years or more. But Obama’s actions also would change enforcement priorities by emphasizing the deportation of new illegal arrivals and criminals.

“I’m surprised they have not detected these 5 million people and have not deported them throughout the years,” Arpaio told KNXV.

Arpaio stated that his lawyer was filing the lawsuit following Obama’s speech and that no taxpayer funds will be used in the lawsuit.

“We have to understand whether this is constitutional or not, whether he is going around Congress is legal,” Arpaio explained to KNXV. “I’m going to send a message that we’re not going to give up, that this does affect the streets of Maricopa County.”

The Maricopa County sheriff fears that Obama’s executive actions will open up the floodgates for those in Central America to come into the U.S.

“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,” Arpaio said.

There are about 300,000 immigrants in Arizona who are in the country illegally, according to report by the Pew Research Center that was released this week. That number has fallen over the past few years as the population of immigrants has shifted from Arizona and other states to the Midwest and East Coast. The number of immigrants who lack legal status has remained the same since 2009 at 11.2 million.

In Arizona, immigration has been an especially difficult battleground for immigrant advocates as the state has passed a series of immigration crackdowns. The most well-known, SB1070, requires local police to check the immigration status of people they encounter while enforcing other laws.

Arizona Gov. Jan Brewer slammed Obama for what she called “brazen, unilateral action that will only further exacerbate the border problem,” just like he did when he issued an order giving legal status to children of immigrants in 2012.

“This is not a partisan issue,” Brewer said. “When the bluest of blue states – like Oregon, for example – vote overwhelmingly to prohibit illegal aliens from obtaining drivers licenses, it speaks volumes about the widespread lack of support for President Obama’s immigration policies. The American people have spoken, and time and again they have been ignored.”

Obama wants to make sure immigrants eligible for his program do enroll. Advocates fear that with only two years left in Obama’s presidency and with Republican threats to undo the executive actions, eligible immigrants won’t sign up.

Without enrollment by millions of immigrants seeking to obtain work permits, these advocates fear, Obama’s executive order would become an easy target for a new president with a different immigration agenda.

Still contending with a spike of Central American migrants who crossed the border this summer, Obama is also eager to draw attention to the southern border in hopes that his actions don’t create an incentive for more attempted crossings.