Ballots are prepared to be tabulated for Maine's 2nd Congressional District's House election in Augusta, Nov. 12, 2018. The election is the first congressional race in American history to be decided by the ranked-choice voting method that allows second choices. Credit: Robert F. Bukaty | AP

After years of debate and legal challenges (including one pending in the courts), Maine became the first state to elect a congressman using ranked-choice voting.

Now the question is, who will follow?

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Democrat Jared Golden was crowned the winner in Maine’s 2nd Congressional District race on Thursday, unseating two-term incumbent Republican Bruce Poliquin, who is challenging the voter-approved law’s constitutionality in federal court. A hearing is scheduled for Dec. 5, and Poliquin’s lawyers have asked that a ruling be handed down before the Dec. 14 deadline for election results to arrive at the U.S. House of Representatives in Washington.

That legal challenge aside, some observers see potential for Maine’s historic election to set a national trend.

The success or failure of ranked-choice voting in Maine “will either fuel the adoption of ranked-choice voting in other jurisdictions, or it will stop it in its tracks,” Corey Cook, the dean of the School of Public Service at Boise State University, who has studied 100 elections that used the system, told the Associated Press.

Patrick Potyondy, a legislative policy specialist with the National Conference of State Legislatures’ Elections and Redistricting Program, has written that ranked-choice voting is gaining traction nationally as an election reform, with lawmakers in 19 states introducing legislation to allow some form of ranked voting.

Ranked-choice voting is used in more than 10 U.S. cities, including in Portland where it has been used to elect a mayor since 2011. Six states also use it for overseas ballots.

Still, no state legislature has taken the plunge and approved the voting system, according to Potyondy.

[What exit polling reveals about Maine’s experience with ranked-choice voting]

A BDN exit poll on Election Day found about 53 percent of respondents wanted to keep the voting method and expand its use to the election for governor. Voting experts say that Maine’s experiment with ranked-choice voting could give proponents a boost as they make the case for the system in other states.

“Other state reform efforts have watched the Maine innovation with great hope and interest, and now they’re seeing it actually implemented,” Larry Diamond, a senior fellow at Stanford University’s Hoover Institution, told the Portland Press Herald. “I think we will look back on Maine’s adoption of this initiative as a real watershed in the history of present-day electoral reform in the United States.”

Even before Maine’s results were in, voters in Hampden County, Massachusetts, approved a ballot question on Election Day to adopt ranked-choice voting, while residents of Memphis, Tennessee, where ranked voting was approved by voters a decade ago but has yet to be used, rejected a measure to repeal the system’s use in municipal elections.

Maine’s experiment with ranked-choice voting has galvanized proponents who see the method as a way to curb the growing partisan divide in U.S. politics.

“[T]he effect on Election Day is just part of the benefit of RCV, and maybe not even the most important. Much more significant is its effect on the campaign itself,” Lawrence Lessig, the Roy L. Furman professor of law and leadership at Harvard Law School, wrote in a USA Today OpEd. “Candidates in a ranked-choice system have a real interest in playing nice.”

The idea is that voters can divide their loyalties among multiple candidates, something that could motivate candidates to use less hostile campaign tactics to secure second- and third-place votes to remain viable in the event of an instant runoff.

[Tired of nasty elections? The fix isn’t as easy as ranking 1, 2, 3]

For that reason, Lessig believes states like New Hampshire should look into adopting the system ahead of its first-in-the-nation presidential primary in 2020.

But the division in the electorate is at an historic high, with majorities of Democratic and Republican voters viewing the opposing party “very unfavorably,” according to the Pew Research Center. That could prove a difficult mindset to dislodge.

“It’s not going to be quick [a return to civility],” Daniel Shea, director of the Goldfarb Center for Public Affairs and Civic Engagement at Colby College in Waterville, told the BDN in 2016. “There’s a whole bunch of forces [at work] that likely won’t change.”