PHOENIX — Arizona officials are seeking legal guidance on rules for filling a Senate vacancy in the event that U.S. Sen. John McCain, who is battling cancer, retires or dies in office.

Secretary of State Michele Reagan's office is asking state Attorney General Mark Brnovich's staff for direction on applicable deadlines for dealing with a Senate vacancy, The Arizona Republic reported .

Lawmakers earlier this week sent Gov. Doug Ducey a bill that would expand the timeframe required to fill future Senate vacancies. It would not apply to McCain's seat if he vacated it in the next few months.

The legislation would take effect 90 days after the Legislature adjourns its current regular session, which would be after current ballot deadlines.

McCain, 81, has served as an Arizona senator since 1987. He has recently dealt with health complications stemming from cancer and has not been in Washington, D.C.

He wrote in his upcoming memoir, "The Restless Wave: Good Times, Just Causes, Great Fights and Other Appreciations," that his sixth term would be his last. The book is set for release May 22.

Under Arizona law, counties are expected to receive at least 120 days' notice before the regular primaries of all state and federal races on the upcoming ballot, said Joe Kanefield, a former state elections director.

"The counties have to know who is on the ballot, and the public has to know who is on the ballot, and the candidates have to know who is on the ballot," he said.

Ducey has not commented on the legislation.

Governors are responsible for appointing a replacement for vacancies in the U.S. Senate. The appointed senator must be from the same political party as the former senator and would serve in the office until at least the next general election.