When voters go to the polls this November, they’ll decide whether to overhaul how Mainers elect representatives to Washington and Augusta, swapping the state’s current either/or system for one in which voters rank candidates in order of preference.

Under ranked-choice voting, also known as instant-runoff voting, voters rank the field of names on a ballot, selecting a first choice, second choice, third choice and so on, creating an instant runoff when no candidate receives more than 50 percent of the first-choice votes.

“With ranked-choice voting, you don’t have to choose between the lesser of two evils,” Kyle Bailey, campaign manager for the Committee for Ranked-Choice Voting, said. “You have the freedom to elect the candidate you think is the best for the job without the fear of electing the person you liked the least.”

However, researchers have found that, put into practice, ranked-choice voting could have the unintended consequences of reducing voter turnout and leading to higher numbers of disqualified ballots when voters make mistakes, potentially worsening inequalities within the electoral process.

“When we make voting changes, they often have unintended consequences,” Jason McDaniel, a political scientist at San Francisco State University, said. “They often seem to affect in a negative way marginal populations, and they are more likely not to engage in political participation.”

Election reformers argue candidates will campaign more civilly under ranked-choice voting, but the flipside is that a more complex ballot could reduce voter turnout.

Today, Maine voters select only one candidate for each position, no matter how many names appear on the ballot, and whoever takes the most votes is the winner, even if the candidate doesn’t earn a majority.

That would change with ranked-choice voting. A candidate would no longer just be fighting for votes but also second- and third-place positions. According to Bailey, that means a candidate would have an incentive to campaign less negatively in order to appeal to a broader cross-section of voters, not just a specific base of voters.

The idea behind this calculus is that it will empower moderate candidates who might not be the first choice of a majority of voters — because ideologically similar candidates might attract support from the same pool of voters, the so-called “Nader effect” — but may be an acceptable second choice for a majority.

Voters who are likely to support third-party and independent candidates may be more motivated to turn out to vote because they will feel empowered to express their preference without feeling as though they “wasted” their vote, Bailey said.

But McDaniel of San Francisco State University found that giving voters the option to rank multiple candidates in order of preference can lead some voters stay home on election day. His research, published last October in the Journal of Urban Affairs, shows that voter turnout in San Francisco — which began using ranked-choice voting to elect mayors in 2004 — declined because of the lack of a simple yes-or-no choice.

Between 1995 and 2011, turnout in mayoral elections declined markedly among voters with a high school education or less and among younger voters. In his research, McDaniel found that navigating the more complex ranked-choice ballot was the reason.

“The increased costs associated with voting in an IRV/RCV election fall most heavily on the youngest and least educated,” McDaniel wrote. “At the other end of the spectrum, sophisticated voters — those who have the highest levels of education and are most interested in and involved with the political process — appear to be better able to navigate the higher information costs and are less likely to be negatively affected.”

Under the fall ballot initiative in Maine, elections for Congress, the Blaine House and the Legislature would be subject to ranked-choice voting. McDaniel cautioned that turnout typically is lower in local elections than in state and federal contests, which could lessen the downward pressure on turnout he found looking at San Francisco elections.

Ranked-choice voting is touted as a path to uncovering the hidden consensus behind a plurality, yet it is no guarantee of a true majority.

Proponents of ranked-choice voting often point to recent contests for the Blaine House, which have featured as many as six candidates splitting the vote, as races that would have seen different results if voters had the option to rank candidates.

Since 1974, only two governors in Maine have won the support of more than 50 percent of voters, including Gov. Paul LePage, who was elected and re-elected with 38 percent and 48 percent of the vote, respectively.

“They aren’t accountable to broad interests within the public,” Bailey said. “This would ensure majority rule and that no candidate [who is] opposed by a majority of voters wins.”

Even under ranked-choice voting, it’s possible for candidates still to win without a majority of all votes cast.

Here’s why.

When votes are redistributed during an instant runoff, ballots can be tossed out or exhausted if voters mistakenly rank more than one candidate, say, as their second choice or if they do not rank all candidates.

Political scientists Craig Burnett and Vladimir Kogan sought to find out how exhausted ballots might affect the outcomes of elections in which ranked-choice voting was used and whether it can lead to candidates still winning with less than a majority.

In a 2015 study, the political scientists from the University of North Carolina at Wilmington and Ohio State University found that in four local elections in California that employed ranked-choice voting, none produced a winner who captured a majority of all votes cast. They found that high rates of ballot exhaustion — ranging from 9.6 percent in a 2010 election in San Leandro to 27 percent in a 2011 contest in San Francisco — led candidates to win on average with 45 percent of the total vote.

“IRV need not, and frequently does not, produce a winner who wins a majority — rather than a plurality — of all votes cast,” Burnett and Kogan wrote.

Portland, the only city in Maine that uses ranked-choice voting, saw a similar result in its 2011 mayoral election. In that election, 19,728 votes were cast for 15 candidates, plus some write-ins. Over the course of 14 instant runoffs, 3,494 ballots were exhausted and Michael Brennan emerged in the final runoff as the winner with 9,061 votes, or 46 percent of all votes cast.

The 2015 mayoral election, however, had a much different outcome. With a slimmed down candidate pool of only three candidates, Ethan Strimling emerged victorious in the first round with 9,163 votes, or 51 percent of all votes cast.

It’s not uncommon for a winner to be crowned in the first round in a ranked-choice contest. Since 2004, there have been 107 elections in the San Francisco Bay Area decided with ranked-choice voting; 68 were won in the first round, according to Bailey.

Here’s the rub. Only 11 cities across the U.S., including Portland, have used ranked-choice voting to elect candidates to local office since 2002, according to FairVote, a nonprofit that advocates for the model.

What research there is on ranked-choice voting is hampered by limited data. The findings that voter turnout goes down and that voter error leads to high rates of discarded ballots could fade over time as voters adjust to the new voting system, McDaniel said.