Voters could be waiting for days or even weeks after the polls close Tuesday to learn which candidates won some of  Maine’s highest-profile elections, because of the state’s ranked-choice voting system.

An unprecedented level of absentee voting, an expected high turnout and potential disruptions at the polls will complicate the job facing state and local election officials, although several say they expect to get results in most races.

Tuesday will be the first time in U.S. history that a state applies ranked-choice voting to a presidential election, as Mainers choose among President Trump, Joe Biden and three minor candidates. The ranked-choice system will also apply in the four-way U.S. Senate race, in which polls indicate that neither of the leading candidates – incumbent Republican Susan Collins or Democratic challenger Sara Gideon – has a majority of votes.

There’s always an outside chance that a landslide could occur in either of these races in Maine, which would mean that winners, based on unofficial results, could be declared not long after the polls close at 8 p.m. Tuesday.

But expert political observers say we probably shouldn’t count on that. Consistent polling in the U.S. Senate race has shown that the contest between Collins and Gideon is close to a dead heat, with Gideon usually leading within or just beyond the polls’ margins of error.

“I think we obviously are not going to know who won some of these elections on Tuesday night,” said University of Maine political science professor Mark Brewer.

Voters will also choose two U.S. House members, with 1st District Rep. Chellie Pingree and 2nd District Rep. Jared Golden, both Democrats, running against Republicans Jay Allen and Dale Crafts, respectively. Polls indicate that both incumbents appear to have good chances of winning re-election, and there are no third-party candidates on the ballot, so ranked-choice will not apply in either of these races.

Mainers will also fill all 186 seats in the Legislature, but under the Maine Constitution, winners of state elections are determined by plurality, so ranked-choice voting cannot be used in those races.

The ranked-choice process allows voters to rank contenders in races with three or more candidates in order of preference. If no one wins a majority after the first tally, election officials eliminate the last-place finisher and redistribute that candidate’s votes based on each voter’s second choice. This process continues – with candidates eliminated from the bottom up and their votes reallocated – until only two candidates remain, and the one with the most votes wins.

Election workers verify, unfold and scan ballots at Kennebunk Town Hall on Saturday. Gregory Rec/Staff PhotographerThe Senate race also features two independent candidates – Max Linn, a conservative running to Collins’ right, and Lisa Savage, a progressive running to Gideon’s left – who are expected to pull some first-choice rankings from the two front-runners. That means the race could be determined by the second or even third choices of the Linn and Savage voters, said Dan Shea, a government professor at Colby College in Waterville. Savage has been urging her supporters to rank Gideon second.

That could spell trouble for Collins, said Shea, who, like Brewer, regards ranked-choice voting as “kind of the one snag we have in all of this.” Shea said voters hoping to know who won should prepare to be patient.

State polling on the race between Trump and Biden suggests Biden enjoys a big lead in Maine’s more liberal, populous and southern 1st Congressional District, and an overall lead statewide.

Election worker Frank Nedeau-Slatttery feeds a ballot into a scanning machine at Kennebunk Town Hall on Saturday. Gregory Rec/Staff Photographer

But the race is tighter in Maine’s more rural and northern 2nd Congressional District, which Trump won in 2016 by 10 percentage points.  If neither Trump nor Biden wins more than 50 percent of the vote in either of the two congressional districts or in the contest statewide, that race, too, would require a ranking tabulation process in Augusta.

The winner would be chosen by tabulating the second- or third-ranked choices of ballots cast among the minor presidential candidates – Green nominee Howie Hawkins, Libertarian nominee Jo Jorgensen and Alliance nominee Roque “Rocky” De La Fuente.

Maine is one of only two states to split its Electoral College votes by congressional district, with the winner of each district receiving one of the four votes and the winner statewide receiving the other two.

If determining a winner requires ranked-choice tabulation, the process shifts from local town halls to the Secretary of State’s Office in Augusta. Encrypted memory devices from ballot-scanning machines and paper ballots from towns that do hand counts would have to be transported to the state capital for tabulation.

That process can take between a week to a week and a half to complete, said Kristen Muszynski, a spokeswoman for Secretary of State Matt Dunlap. State law doesn’t require that election results be made known on the night of the election, and Dunlap and his staff have 20 days to certify official results and issue the official tabulations. Under the law, local election officials have two days to get their final results to Dunlap, Muszynski said.

Local election officials have said they feel well-prepared to administer the election on Tuesday. The turnout on that day may be relatively light compared to previous presidential elections, as many voters have cast absentee ballots early to avoid exposure to the COVID-19 virus at the polls.

As of Friday, close to 50 percent of the state’s 1.06 million registered voters had already returned their absentee ballots. Election clerks began processing those ballots last week, under an executive order from Gov. Janet Mills that eased ballot handling restrictions in state law. The absentee ballot processing will continue through Election Day.

However, the tallies for absentee voting are not calculated until after the polls close at 8 p.m. Tuesday, when they are then added to the tallies from in-person voting to reach final results.

City clerks in Maine’s two largest cities, Portland and Lewiston, said Friday they are optimistic they will complete all their counting on Tuesday night and said they should have unofficial results available sometime later that evening.

Election workers verify, unfold and scan ballots at Kennebunk Town Hall on Saturday. Gregory Rec/Staff Photographer

Jessica Grondin, a spokeswoman for the city of Portland, said election officials there are “hopeful” they will have results on Tuesday night. She pointed to the extra time provided for early processing of ballots under Mills’ order, and a new high-speed ballot-scanning machine that helps expedite that process.

The city saw delayed results during primary voting in July, largely because of the high volume of absentee votes and because it did not have the high-speed ballot-scanning machine at that time.

Lewiston City Clerk Kathy Montejo said she was hopeful her unofficial results would be available by 11 p.m.

But ongoing and intense voter interest in both the presidential race and the U.S. Senate race could throw clerks a curveball if in-person voter turnout is heavier than expected, Montejo said.

“Unknown factors that will delay it will be how many voters are still in line at 8 p.m.” she said. “Everyone in line then can still vote, so the workers won’t be able to close down and start tallies at 8 p.m. like usual. And of course we won’t know if anyone will be in line at 8 p.m. until 8 p.m.”