Republican Arizona Gov. Doug Ducey signed a bill on Wednesday requiring all residents of the Grand Canyon State to provide proof of citizenship and residency in order to register to vote in federal elections.

“Election integrity means counting every lawful vote and prohibiting any attempt to illegally cast a vote,” the governor wrote in a letter backing the bill, calling it a “balanced approach” to making voting accessible and protecting elections. 

Previously, Arizona law mandated citizens provide citizenship and residency proof for state elections only. Arizonans looking to vote in federal elections only needed to attest under penalty of perjury that they are a citizen, but did not have to provide proof. 

Ducey claimed in his letter that more than 11,000 voters in the 2020 general election had not provided proof of citizenship, up from a mere 21 in 2014. 

The new legislation will require election officials to verify the citizenship status of all voters submitting a federal voter registration form that does not include the necessary proof. 

If non-citizens register to vote, the state’s Attorney General’s Office will likely investigate and prosecute under Arizona statutes.

Arizonans who registered to vote before 2004 — when the state implemented its order to require citizenship for state elections — and have not provided proof to election officials will not be affected by the law, Ducey claimed. 

The legislation is scheduled to go into effect 90 days after the final day of Arizona’s legislative session, April 19.  

State Rep. Jake Hoffman, the Republican sponsor of the bill, said he was confident the legislation will survive any legal challenge.

“HB2492 is an incredibly well-crafted piece of legislation that is on sound legal footing and broadly supported by voters of all political parties,” he told CNN on Wednesday. “I am confident that should Democrats challenge HB2492 in court it will only serve to further reinforce its clear constitutionality.”

The newly signed law is expected to be challenged due to a 2013 Supreme Court ruling that said Arizona cannot require voters who register on federal forms to provide proof of citizenship.

Some critics say the legislation will harm voters who lack a valid state driver’s license or identification card or do not have the documentation readily available — such as students, elderly residents and Native Americans. 

Also Wednesday, Ducey signed several other controversial bills, including a ban on abortions after 15 weeks, a measure preventing transgender girls from playing on women’s sports teams and outlawing gender confirmation surgery for anyone under 18.