The Senate could vote next week on a whether to seek a Maine Supreme Judicial Court opinion on the constitutionality of the state’s new system of ranked-choice voting.

Last November, Mainers approved an initiative that would allow voters to rank candidates for governor, Congress and the Legislature in order of preference, thereby enabling an “instant run-off” in the event that no candidate receives a majority of the votes in the initial tally. Maine would be the first state in the nation to adopt ranked-choice voting for statewide elections beginning in 2018. However, opponents have questioned the constitutionality of the system.

Next week, the Maine Senate is expected to vote on a procedural order that, if it passes, would ask Maine’s highest court to weigh in on the constitutionality issue. Approval of the order – known as a “solemn occasion” request – would require a majority vote in the closely divided Senate.

“Whether you support this or not, we do not want to put our election system and our elections into chaos,” Senate President Mike Thibodeau, R-Winterport, said Wednesday. “We need clarity from the courts as to whether or not this is constitutional. And if they come back, as I suspect, with a ruling that says it is unconstitutional, then we will have a significant amount of work to do before our next election cycle.”

Critics of ranked-choice voting – including Attorney General Janet Mills – have suggested that the initiative may violate a provision of Maine’s Constitution that state lawmakers, the governor and members of the Congress are elected by “a plurality of votes.” They also questioned the constitutionality of having the voting results tabulated by computer at a centralized location rather than by municipal election clerks.

Thibodeau said the Legislature would have two choices if Maine Supreme Judicial Court ruled the initiative is unconstitutional: either change the Maine Constitution or take action to reverse the ranked-choice voting citizen’s initiative.

“Hopefully the court will take it up and not leave us in a very tough position which would be to hold elections under a set of rules and laws that potentially are unconstitutional and throw our elections into turmoil,” said Thibodeau, an opponent of the ranked-choice voting initiative that appeared as Question 5 on the November ballot. The initiative passed with 52 percent of the vote.

Under ranked-choice voting, voters rank candidates in order of preference. If no candidate gets more than 50 percent of the top votes cast after the first tally, the candidate with the fewest votes is eliminated. Voters who chose the eliminated candidate have their ballots added to the totals of their second-ranked candidate and the ballots are retabulated. This process continues until one candidate has a majority of votes and is declared the winner.

While ranked-choice voting is sometimes called “instant run-off,” the results would not be instantaneous in Maine in the event that a candidate failed to win a majority of votes during the first tally. That’s because a statewide tabulation of results would have to take place via computer at the Secretary of State’s office or some other centralized location.

Maine Secretary of State Matt Dunlap has questioned whether the state could feasibly implement the ranked-choice voting system by 2018.