But there was no widespread chaos, and proponents were already talking up expanding the system Wednesday, even before the votes were fully tallied.
Growing ranked-choice voting in Maine alone will take a long-odds amendment to the state's constitution, but backers said that's just a step along the way to getting more states on board with a system they believe gives voters more options and more voice.
"Ranked-choice voting is the change we need to get more voice to the people, and it's here to stay," said Kyle Bailey, manager for the ranked-choice voting campaign.
Residents voted Tuesday to retain the voting system, nullifying a legislative delay and allowing it to be used in November's federal elections in Maine.
There were hiccups. Some voters just couldn't understand why they were being asked to vote on ranked-choice voting while using the new system, said Bangor municipal clerk Lisa Goodwin.
Goodwin estimated Bangor saw 150 spoiled ballots, compared to 25 to 30 in a typical election. The wording of the referendum question also confused some voters, she said.
But voters like Democrat Brad Messier, of Brunswick, enthusiastically embraced the new system, even though it means they won't know the result of the Democratic primary for several days.
"I think that's about the most specious argument - that you have to wait," he said Wednesday. "This is government. It isn't ordering a hamburger or fast food. We want a quality system. It takes a little time."
Ranked-choice voting works like this: Voters rank candidates from first to last on their ballots. A candidate who collects a majority of the vote wins. If there's no majority, then the last-place candidate will be eliminated and votes reallocated. The process is repeated until there's a majority winner.
The voting system is used in 11 local jurisdictions and was used for the first time in a U.S. statewide primary Tuesday.
But it has plenty of critics, including the governor. Republican Gov. Paul LePage said Tuesday that he probably won't certify election results. There's also the possibility of a lawsuit. Maine Supreme Court Justice Donald Alexander mused during previous arguments about whether the voting system might have violated the "one man, one vote" concept.
"I don't think it's going out on a limb to say that there will be at least one lawsuit. I'll take that bet," said University of Maine political science professor Mark Brewer.
Republican businessman Shawn Moody was a majority winner Tuesday. But no one came close to getting an outright majority to claim victory in the seven-candidate Democratic gubernatorial primary Tuesday.
That means ballots will be shipped to Augusta, Maine, for more tabulations next week under the state's ranked-choice voting system.
In Maine's 2nd Congressional District, Marine Corp veteran and state lawmaker Jared Golden had the most first-place votes in Maine's Democratic congressional primary. But it'll likely take additional tabulations in that race to determine if he's earned the right to challenge Republican Rep. Bruce Poliquin in November.
That likely puts Golden and Lucas St. Clair, who led a push for a national monument, in the same boat in the 2nd District as Attorney General Janet Mills and attorney Adam Cote in the Democratic gubernatorial primary.
A constitutional amendment would address a major shortcoming by allowing the system to be used in the governors' race, where nine out of the last 11 elections failed to produce a majority winner.
At present, ranked-choice voting can't be used in state general elections because of state constitutional concerns. But amending the constitution is easier said than done. It can't be done without the support of Republicans who in the summer of 2017 scuttled a legislative effort to start the process of changing Maine's constitution.
Republican Fryeburg voter Zac Mercauto, who voted against keeping the ranked-choice system, said he's open to the possibility of keeping it if it can be made more efficient and squared with the constitution.
"I just want it tweaked so the results come in a little quicker, unlike what's going on on the Democratic side right now," he said.
Associated Press writer David Sharp contributed to this story in Portland.
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