In the state of Maine, winners of elections were previously decided by plurality (where the person with the most votes wins). This year in 2018, voters of Maine decided that they wanted to use a ranked choice method of voting. This means that candidates must achieve a majority of the votes (51%) in order win. (Read more about ranked choice here).
The primaries for Maine happened back in mid June, where candidates from each party were nominated for governor. This was the first state-wide election to ever use a ranked choice ballet in the country.
Republicans of Maine, who won the last election by plurality, fear that this new method of voting hurts their chances of winning this election. In 2010, republicans only won they election by about two percent over the democratic nominee. In that election, there was a left-leaning independent who took a decent amount of votes away from democratic nominee. In a ranked choice election, there is only two candidates left for the final vote. People that voted for independent candidate originally, would more than likely swing there votes toward the democratic candidate which could of switched the election results entirely.
You can read more about Maine’s new system here: