Gov. Doug Ducey of Arizona has signed legislation requiring voters to prove their citizenship in order to vote in a presidential election, swiftly drawing a legal challenge from voting rights activists who argued that it could keep tens of thousands of voters from casting a ballot.

The Arizona measure, passed into law on Wednesday, also requires newly registered voters to provide a proof of address, which could have a disproportionate impact on students, older voters who no longer drive, low-income voters and Native Americans.

Legal experts said the new rules might run afoul of both federal law and recent Supreme Court decisions. On Wednesday, Mi Familia Vota, a voting rights group, filed a federal lawsuit challenging the law.

The law is one of several new voting restrictions that the Republican-led Legislature in Arizona is working to pass this year, despite multiple investigations and a partisan election review that found no evidence of widespread fraud in the state in the 2020 election.

It is the latest sign that the push by Republican lawmakers to tighten voting rules after the 2020 election has not abated. G.O.P. lawmakers in Mississippi, Idaho and other states have also proposed new identification requirements. And legislators in Georgia and Florida have advanced a second round of major changes to election laws.

Arizona Republicans said that the law would shore up election security, although they did not point to any evidence of significant fraud.

“Election integrity means counting every lawful vote and prohibiting any attempt to illegally cast a vote,” Mr. Ducey said in a letter explaining his support for the legislation. Speaking to local reporters, he defended the constitutionality of the law. “If somebody on the left wants to challenge it, have at it,” he said, according to The Arizona Republic. “Nothing’s unconstitutional unless it’s an enumerated right and that’s not what this law is.”

But lawyers for the Republican-controlled Legislature had previously suggested that the bill could flout federal law.

In 2013, the Supreme Court ruled that Arizona could require proof of citizenship in state elections, but that it must accept the federal voter registration form for federal elections. Those forms ask voters to attest that they are citizens but do not require documentation.

The decision set up a bifurcated system in Arizona. There are now roughly 31,500 “federal-only” voters in the state, or people who are not eligible to vote in state elections because they have not provided documents that prove citizenship as required by Arizona law, according to the secretary of state’s office.

The new law essentially contradicts the Supreme Court decision, forcing all voters to meet the state’s requirements for a presidential election.

In testimony before the Arizona House’s Rules Committee last month, Jennifer Holder, a lawyer for the Legislature, told Speaker Rusty Bowers that the issue had “been squarely addressed by that Supreme Court case.”

Legal experts said the new law could be a vehicle to challenge the 2013 Supreme Court ruling, and could push the court to re-examine broader voting laws and regulations.

“It certainly is attempting to undo the Arizona v. I.T.C. decision,” said Jon Greenbaum, chief counsel for the Lawyers’ Committee for Civil Rights Under Law, referring to the 2013 Supreme Court decision. “And maybe part of this is thinking you’ve got a new Supreme Court now, and that Supreme Court may look at things differently.”

Critics of the Arizona law say that its impact extends far beyond 31,500 voters, and that it could cause many more people to be pushed off the rolls.

“Those people won’t get their ballot in the mail,” said Alex Gulotta, the state director for All Voting Is Local, a voting rights group. “They may go try and vote and they’ll find out they’re no longer registered and it’s too late to register, and they will in fact be disenfranchised for this election in November.”

The worries about tens of thousands of additional voters losing their registration are rooted in a 1996 state law that requires proof of citizenship to obtain a driver’s license. Because of that law, the state could assume that anyone registering to vote with a driver’s license had already proved their citizenship status. But 192,000 people in Arizona have pre-1996 driver’s licenses, according to the state’s Department of Transportation.

Sam Almy, a Democratic strategist, sought to estimate a partisan breakdown of who would be affected by the new law by comparing those who had not updated their voter registration in Arizona since 2004 with a Democratic voter file. According to Mr. Almy, 45 percent of potentially affected voters were Republicans, compared with 36 percent who were Democrats. Nearly 90 percent of the voters were over the age of 50.

Mr. Greenbaum said it was unclear whether the new law would immediately be applied retroactively to affected voters. He also said that it was unclear if any would be notified if their registration had become invalid.

As in other states, local election officials in Arizona have been strained by limited funding, threats to their safety and new, graver penalties for mistakes.

A bipartisan group of local election officials asked Governor Ducey in a letter last week to veto the bill, criticizing its “unconstitutionality” and saying that it would put “county recorders and election officials in the untenable position of trying to comply with state law while at the same time clearly violating the federal National Voter Registration Act.”

Local election officials warned of another logistical headache: The law, as signed, would go into effect 90 days after the Legislature adjourns for the year, which could be as late as June. But Arizona’s primary election is set for Aug. 2, which could mean that the primary will be held under the old laws and the general election will have to abide by the new law.

“Election administrators have been fighting misinformation and disinformation for years now, and they’ve been trying desperately to keep up with the shenanigans of the extreme political right,” said Adrian Fontes, the former election administrator for Maricopa County and a Democratic candidate for secretary of state in Arizona.

“They’ve been planning on this election for a year and a half now,” Mr. Fontes continued, “and for these curveballs to get thrown at election administrators at the last second to impact so many tens of thousands of voters across the entire state — there’s a lot of county recorders out there that are just going to be scrambling, and I feel for them.”