AUGUSTA — The state Senate gave final approval Monday to a bill that would allow Mainers to use ranked-choice voting during the presidential primaries in March.

It was unclear heading into Monday’s special session whether the  Senate would take up the bill to allow voters to rank candidates when they head to the polls on March 3 to participate in the Super Tuesday presidential primary elections.

But after Republicans blocked three of the four bond packages that were the central focus of Monday’s session, Democratic Senate President Troy Jackson revived his ranked-choice voting bill and put it to a vote just before 6 p.m.

The bill passed on a largely party-line vote of 20-12 and is now headed to Gov. Janet Mills, who has not signaled how she will respond. Mills won the Democratic nomination for governor in June 2018 following the nation’s first use of ranked-choice voting to decide a statewide election.

“It bothered me that we had a bill and if we didn’t do it today, it wouldn’t go into effect for Super Tuesday because there would have been no way to enact it in time,” Jackson, D-Allagash, said in an interview. “I’m still thinking about those two referendums for ranked-choice voting. I don’t think I have to apologize for that. That’s what the people have voted for twice.”

Lawmakers voted in June to join the vast majority of states that use statewide primary elections — rather than more complicated and time-consuming local caucuses — to help select parties’ presidential nominees.

There is now a “people’s veto” petition circulating to block the presidential primary vote. But unless that campaign can collect enough signatures by mid-September, Mainers will join voters in 14 other states in casting ballots on March 3.

Jackson’s bill to use ranked-choice voting during those presidential primary elections received initial approval in both chambers of the Legislature but was shelved during the final hours of the 2019 legislative session. Ranked-choice voting supporters were at the State House on Monday, urging senators to revive the bill so that voters would have the option of using the process during what is still expected to be a crowded, fiercely competitive Democratic presidential primary.

“Senate President Jackson and the Senate Democratic caucus really delivered for Maine voters,” said David Farmer, a spokesman for the Committee for Ranked Choice Voting, which led the two ballot campaigns to pass and then reaffirm the state’s use of the process. “We knew it was a tough vote to take during the special session, but we are grateful they felt it was important that voters have ranked-choice voting (option) during the March primary.”

Maine is the first state to use ranked-choice voting in statewide elections.

The process allows voters to rank contenders in races with three or more candidates in order of preference on the ballot. If any candidate receives 50 percent or more of the vote on the first tally, he or she is declared the winner and the election is over. If no one receives a majority, however, the candidate with the least number of votes is eliminated and that candidate’s votes are reallocated to the candidates that their supporters ranked second.

That process continues – with candidates eliminated from the bottom up and their supporters’ votes redistributed – until one candidate secures a majority of the remaining vote pool.

Ranked-choice voting is now used in primary elections for governor and the Legislature and in both primary and general elections for Maine’s representatives to Congress. Jackson’s bill, L.D. 1083, would add presidential primaries to that list if it is signed or allowed to become law by Mills.

“The governor has said in the past that she supports ranked-choice voting and we hope that holds true,” Farmer said.