PHOENIX — The Court of Appeals on Thursday opened the door for Republican legislative leaders to argue that candidates have a constitutional right to take more money from private donors than has been allowed.

In a formal opinion, the judges reaffirmed their earlier order keeping the current limits in place, saying there is evidence legislation pushed through by Republican lawmakers earlier this year increasing campaign donation limits violates a constitutional provision.

But the court also sent the case back to the trial judge, directing Maricopa County Superior Court Judge Mark Brain to consider claims by lawyers for Republican legislative leaders that the old limits — the ones the appellate court just restored — are so low as to violate the First Amendment rights of candidates and donors.

That raises the possibility the old limits could be declared unconstitutional. And if the new limits were improperly enacted, there might be absolutely no cap on how much individuals and political action committees could give, or how much candidates could accept.

At that point it would be up to the Legislature to find a constitutional way of setting legally acceptable limits, assuming lawmakers were interested in doing that.

That isn’t legally necessary: Arizona had no limits before voters put some place in 1986. And a court could not order the Legislature to impose new limits.

That would leave public demand for some sort of limit on campaign funds as the only pressure to act.

For the moment, though, the old limits are in effect for the 2014 campaign. And Mike Liburdi, the attorney for GOP leaders, still hopes to get the Arizona Supreme Court to overrule the appellate judges and allow candidates to start taking more dollars in time to get elected next year.

The fight surrounds a vote by lawmakers to let candidates take up to $4,000 from any one individual or political action committee.

The old limit was $440 for legislative races and $912 for statewide campaigns.

Lawmakers also voted to repeal a cap of $14,688 on how much candidates can take from all PACs for any election, as well as a $6,390 lid on the amount any one individual or PAC can give to all candidates in any year.

But the appellate court agreed with the Citizens Clean Elections Commission that the 1998 voter-approved system of public financing not only cemented in place the limits on private donations that existed at that time, but rolled them back by 20 percent.

Lawmakers cannot alter voter-approved measures without a three-fourths vote of the Legislature, something this legislation did not get.