AUGUSTA — The clock is running out for Gov. Janet Mills to act on a bill that would make Maine the first state in the country to use ranked-choice voting in presidential elections.

Mills received the bill on Aug. 26 during a one-day special session of the Legislature that she called to decide on a series of bonding bills for roads and bridge fixes and other infrastructure.

Under the Maine Constitution, Mills has until midnight Friday to decide whether she wants to sign the bill, veto it or allow it to become law without her signature. A veto likely would kill the legislation because Republicans are staunchly opposed to ranked-choice voting and would ensure that the bill does not receive the two-thirds majority in the House and Senate needed to overturn a veto.

Mills also can hold the measure until the Legislature reconvenes in January, which would make it nearly impossible for it to take effect for a new statewide presidential primary vote in March.

Lindsay Crete, the governor’s press secretary, confirmed Thursday that Mills was still pondering the ranked-choice measure and had until the end of the day Friday to make her decision.

Last week, Mills said that she was wrestling with her decision for several reasons, including how the law would be applied to both the primary in March and the general presidential election vote in November 2020.

“I’m reading the bill carefully (to) see how it impacts not only the primary, but the general election of electors for president, because there is a line in there about how it applies to the election of electors,” Mills told Maine Public.

The governor also said she was concerned that lawmakers had failed to allocate money to cover the cost of the bill for state government. Maine Secretary of State Matt Dunlap said the measure will cost about $100,000 to implement in March.

The ranked-choice process allows voters to rank contenders in races with three or more candidates in order of preference. If no one wins a majority after the first tally, election officials eliminate the last-place finisher from contention and redistribute that candidate’s votes based each voter’s second-choice ranking.

This process continues – with non-viable candidates being eliminated from the bottom up and their votes reallocated – until someone hits the threshold of 50 percent plus one vote. And that person is the winner.

Much of the focus has been on how the bill would affect the March presidential primary, which is likely to have a large number of candidates seeking the Democratic nomination. The primary is unusual because it is not a traditional winner-take-all election. Instead, the results are used by the political parties to allocate delegates to the national conventions. Candidates can win one or more delegates depending on their share of the votes. There is no need to declare a winner or ensure that any candidate gets an outright majority of the votes.

But the bill also calls for the Maine Secretary of State’s Office to apply ranked-choice voting in November 2020. And, in theory, that could lead to multiple ranked-choice instant runoffs because of Maine’s unusual way of choosing presidents.

Maine is one of the two states – Nebraska the other – that splits its Electoral College votes based the outcome of the election in each of the state’s two congressional districts. Maine awards one electoral vote to the winner of each district and two for the overall statewide winner, a process outlined in the state’s constitution.

And while that division is unusual, it occurred in 2016 when Donald Trump won the vote in Maine’s 2nd District while losing statewide and in the state’s more Democratic 1st District. Trump was awarded one of Maine’s four Electoral College votes and Democrat Hillary Clinton was awarded three.

If Mills signs the bill into law, presidential elections in Maine could feature multiple ranked-choice runoffs.

If no candidate wins more than 50 percent of the vote in either of the state’s two U.S. congressional districts or statewide, ranked-choice tabulations would take place to determine the winner of each to allow the state to apportion its four Electoral College votes.

Dunlap’s spokeswoman, Kristen Muszynski, said the Secretary of State’s Office was still determining one of two ways it might apply the bill, should it become law, if multiple tabulations are needed in a presidential general election.

She said the state could tabulate the ballots for each congressional district and then run the statewide tabulation, or it could work with the state’s vendor to write an algorithm so all the tabulations can be done at one time. The cost to the state is not yet known.

Perhaps because of the complicating factors, Mills is taking an unusually long time to decide on the bill. Unlike her predecessor, Republican Gov. Paul LePage, Mills has been relatively quick to decide her position on legislation. LePage regularly used the entire 10 days allowed under the state constitution to ponder bills.

Also unlike LePage, who governed with a divided Legislature and rapidly set a record for vetoing more bills than any governor in state history, Mills has gone relatively easy on the Democratically controlled Legislature with her veto pen, issuing just eight vetoes so far during her first term.

The voting bill came to Mills unexpectedly because the Maine Senate, largely on a party-line vote, enacted the measure, 20-12, after Senate President Troy Jackson, D-Allagash, put it to a last-minute floor vote even though Mills and other State House leaders wanted lawmakers to focus their attention on the bonding packages they were called back to vote on.

Mills also is in an unusual position because she was the winner of the nation’s first statewide ranked-choice election.

Maine was the first state to implement ranked-choice voting in statewide primary races and federal elections, in 2018. So far the process has been applied in only two statewide contests – the 2018 Democratic primary for the governor, won by Mills, and in the 2018 general election contest for Maine’s 2nd District race, which was won by Democratic challenger Jared Golden after a ranked-choice runoff against incumbent Republican Bruce Poliquin.

Ranked-choice voting is not used in Maine for the general election contest for the governor’s office or the Legislature, based on an advisory opinion of the state’s Supreme Judicial Court, which said the Maine Constitution calls for elections to state office to be determined by a plurality.