PHOENIX — Proponents of more time to register to vote say Attorney General Mark Brnovich is having what amounts to buyer’s remorse in failing to defend the deadline in the first place.

In new legal filings, the challengers point out that Brnovich never intervened in the case when they sued Secretary of State Katie Hobbs to force her to move the deadline back from its legally set Oct. 5 date. Instead, someone from Brnovich’s office represented her, unsuccessfully, in that case.

Only after a federal judge set a new Oct. 23 deadline and Hobbs concluded that an appeal is not in the best interest of the state did Brnovich take an interest and decide that he and his office now need to defend the law.

But the lawyers for the challengers are telling the appellate judges that new-found interest in the issue legally comes too late.

The new legal filings underscore what has become an increasingly testy relationship between Brnovich and Hobbs who have disagreed on how to handle previous challenges to election law — and who could end up facing off in the 2022 race for governor.

At the center of the case is the finding this past week by U.S. District Court Judge Steven Logan that the COVID-19 pandemic and the restrictions on travel, gatherings and business operations imposed by Gov. Doug Ducey made it difficult to register people to vote. So he voided, for this year, the deadline of this past Monday and gave anyone who wants to sign up an extra 2½ weeks.

The ruling came over objections by Hobbs who pointed out that Mi Familia Vota and the Arizona Coalition for Change waited to just three business days before the deadline to file suit. She argued that making such a major change so close to the Nov. 3 election would create extra work for county recorders.

Logan was unmoved, pointing out that 31 other states have registration deadlines much closer to the election.

Hobbs decided not to appeal, particularly as the ruling applies only to this year’s election.

“We need to give the voters clarity,’’ said aide Murphy Hebert.

That decision did not sit well with Brnovich who earlier this week asked the 9th Circuit Court of Appeals for permission to now intervene in the case. And in the interim he wants the appellate judges to set aside Logan’s order and immediately stop new registrations.

But attorney Zoe Salzman who represents the two groups that sued is telling the appellate judges to send Brnovich packing.

“He has no independent power to appear in his own capacity now that his client — the state of Arizona’s chief election officer — has made the considered and authoritative judgment that it is not in the best interests of the state to appeal,’’ she wrote.

In fact, Salzman pointed out, Brnovich never even made an attempt to intervene in the case when it was filed. That, she said, put Hobbs in the role of deciding how to defend the law and, more to the point, when to stop.

Salzman noted that Brnovich, a Republican, and Hobbs, a Democrat, have squabbled in other election-related cases.

For example, Hobbs sided with initiative circulators who sought to be able to collect the signatures they need this year online using the existing E-Qual system already available for candidates. Brnovich, who had a role in that case, did not and the court sided with him.

The pair also are on opposite sides of a case before the U.S. Supreme Court on the issue of “ballot harvesting.’’ Hobbs wants the justices to uphold a federal appeals court decision allow the practice of civic groups being able to collect early ballots from those who forgot to mail them in; Brnovich wants to overturn that ruling.

In those cases, Brnovich actually was a party to the case. This time, Salzman said, he chose to sit on the sidelines despite the history of differences he has had with Hobbs.

“He fully well knew that the secretary might make a different decision in this case than he would,’’ she said, yet opted not to intercede.

“That the attorney general is unhappy with how that choice turned out provides no basis for him to change course and declare, contrary to his position in the district court, that he and not the secretary speak for the state in this action,’’ she told the appellate judges.

And that’s not all.

Salzman cited a 1975 Arizona court ruling which concluded that the attorney general does “not have the power to appeal against the wishes of his client.’’ That, she said, means Brnovich is stuck with the decision made by Hobbs not to pursue the case.

Finally, Salzman pointed out that voters chose Hobbs to be the top state officer dealing with elections. To let Brnovich intervene, she said, would be let him claim her powers.

The appellate judges have not said when they will decide whether to allow Brnovich to intervene and whether to consider the appeal of Logan’s decision.