Arizona and Kansas lost an appeal seeking to add proof of citizenship to federal voter registration forms.

PHOENIX — Arizona cannot require people to produce proof of citizenship before they register to vote, at least not for federal elections, the U.S. Supreme Court ruled on Monday.

The justices upheld a ruling by the 10th Circuit Court of Appeals that said neither Arizona nor Kansas can demand the federal Election Assistance Commission add a proof-of-citizenship requirement to the federal registration form the panel designed. More to the point, the form is valid without such proof and Arizona cannot refuse to let those who use it vote.

Monday’s ruling is a setback for state officials in Arizona, finally putting to rest their efforts to enforce a 2004 voter-approved measure mandating such proof.

Its immediate impact, however, is limited.

It does not disturb the requirement for proof of citizenship when people use state-designed voter registration forms. And the Secretary of State’s Office said that, at last count, only 1,135 people had registered using the federal form out of about 3.2 million active voters.

But its implications are far reaching: It makes it more attractive for voter registration groups to now use the federal form to sign people up to vote because they do not have to also submit that citizenship proof. That change could help those who do not have easy access to accepted forms of ID.

There is a tradeoff, however. Those who register with the federal form and do not provide citizenship proof will be able to vote only in federal elections, meaning for president and members of Congress.

Nothing in Monday’s decision allows those who lack the proof to vote in state and local matters.

A spokesman for Secretary of State Michele Reagan said she “respects the ruling” and that counties will continue to accept the federal form without citizenship proof “as commanded by the Supreme Court.”

Proposition 200, the 2004 ballot measure, was part of a broader effort aimed at those not in the country legally.

It requires both proof of citizenship to register and identification when casting a ballot. Proponents said it would ensure that election results are not affected by those voting illegally.

Legal efforts to kill the ID provision failed. And Arizona has been entitled since the 2004 vote to require documented proof of citizenship for those who use state-designed forms to register.

The legal fight stems from the fact that Congress, in approving the National Voting Registration Act, directed the Election Assistance Commission to design a single national voter-registration form to simplify the process. That form requires no proof of citizenship but only that those signing up swear, under penalty of perjury, they are eligible to vote.

In 2013 the U.S. Supreme Court rejected an attempt by Arizona and Kansas, which has a similar law, to enforce the proof-of-citizenship requirement on those using the federal form. But the justices said the states are free to ask the commission to change the form.

That request was rejected. That led to a new appeal which was rejected by a federal appellate court.

Monday’s Supreme Court action upholds that appellate ruling.