Maine is poised to become the first state in the country to implement a system allowing voters to rank candidates in presidential elections.

Democratic Gov. Janet Mills said Friday she would allow the bill to become law without her signature in January 2020, which means that the system won't be used in the state's March 3 presidential primary. Instead, the bill won't take effect until 90 days after the next legislative session adjourns in April or May.

Ranked voting in Maine was approved by voters in 2016 but only used for federal races and primaries. The system was the subject of controversy in 2018, when Republican U.S. Rep. Bruce Poliquin lost his bid for reelection in Maine’s second house district to Democratic opponent, Jared Golden despite having more votes than his closest opponent.

That's because under the ranked voting system, voters categorize a crowded field of candidates from favorite to least favorite. If a candidate fails to win the majority of votes, the last-place finisher is eliminated and the second-choice votes of everyone who ranked that candidate first are allocated until someone receives more than 50 percent.

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Poliquin argued in federal court that ranked voting is unconstitutional because its unique runoff system produces a “faux majority” winner of elections and confuses voters. U.S. District Judge Lance Walker disagreed, ruling that critics can question the wisdom of ranked-choice voting, but that such criticism "falls short of constitutional impropriety."

Supporters of the ranked choice system who have been trying to spread it to more states cheered the expansion Friday. Such advocates hope the law could boost the influence of an independent and third-party presidential candidate in Maine, one of two states that split their electoral votes, and sway the outcome in a tight race.

Mills said Friday that she is confident ranked voting will give "voters a greater voice and it encourages civility among campaigns and candidates at a time when such civility is sorely needed."

Still, she admitted that there were some "serious questions about the cost and logistics of ranked-choice voting, including collecting and transporting ballots from more than 400 towns in the middle of winter, and questions remain about the actual impact of this particular primary on the selection of delegates to party conventions.”

The bill says using ranked voting in presidential races would have a “minor cost increase.” Democratic Secretary of State Matt Dunlap has estimated primaries implementing the new system could cost $100,000.

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“By not signing this bill now, I am giving the Legislature an opportunity to appropriate funds and to take any other appropriate action in the second regular session to fully implement ranked-choice voting in all aspects of presidential elections as the Legislature sees fit,” Mills said.

Opponents of the switch to a primary have until Sept. 18 to submit enough signatures. Then, voters in June would have a chance to weigh in on the law approving the change.

About two dozen cities — Including Cambridge, Mass., and St. Paul, Minn. — allow the use of ranked choice voting in certain elections, according to advocacy group FairVote.

The group says at least a half dozen cities are set to use the system in upcoming elections, while several state Democratic parties, such as in Kansas, plan to use ranked voting in presidential primaries next spring.