PORTLAND, Maine (AP) – Maine’s historic use of a ranked voting system could play a role in the determining the president.

Voters in the state approved adoption of ranked choice voting in a 2016 referendum drive, and the method appears on ballots in a presidential race for the first time in U.S. history this fall.

The voting method had to withstand numerous legal challenges just to remain on the ballot at all. Ranked voting arrives on Maine’s presidential ballots in a year when three of the state’s four electoral votes could be in play.

Former Vice President Joe Biden leads in statewide polls, but President Donald Trump is popular in the rural 2nd Congressional District.