By Daniel Trotta
PHOENIX (Reuters) - Arizona voters may have to wait a week or more to learn whether their U.S. senator is Republican Martha McSally or Democrat Kyrsten Sinema, as some 600,000 ballots remained uncounted as of Wednesday afternoon.
With one out of every four ballots remaining to be counted, McSally led by about 15,000 votes, less than one percentage point. Neither candidate was ready to concede, though the outcome was unlikely to tip the balance of power in the U.S. Senate after Republicans flipped three seats in their favor, extending their majority.
The delayed result is a familiar feature of Arizona politics, when candidates can wait for days or weeks to learn final results.
That is because of a state law that gives voters the choice of mailing in early ballots or dropping them off at polling places as late as Election Day, requiring time to be hand-processed.
"I can relate. When I ran in 2016, I had to wait 10 days for my final results," said Maricopa County Recorder Adrian Fontes, who in his elected position is responsible for overseeing the count of the nearly 500,000 ballots yet to processed in Arizona's largest county.
Hundreds of poll workers will hand-process the ballots in a county warehouse, which could take eight or nine days, Fontes said in a telephone interview.
The Secretary of State's office will certify the results on Dec. 3, though the winner may become clear before then as the vote count gets gradually updated.
"We don't think of it as quirky. We think of it as enabling as much participation in the process as possible," Arizona Republican political strategist Stan Barnes said. "Out west, we tend to take our time with these things."
Only about 20 percent of Arizona voters actually went into the voting booth on Tuesday, with 80 percent dropping off or mailing ballots, said Matt Roberts, a spokesman for Arizona Secretary of State Michele Reagan.
In recent years, Arizona voters have waited later and later to drop off their ballots, Roberts said.
"There's no law against them holding onto their ballot until the last minute but it certainly causes a delay for close races," Roberts said.
McSally has been through the wait before. She won her House of Representatives race in 2014 by a razor-thin margin more than a month after the election.
That race also involved litigation, and a Superior Court judge declared her the winner by 167 votes over incumbent Democrat Ron Barber following a state-mandated recount.
Neither campaign responded to a request for comment on the wait.