Montana requires a petition of 5,000 signatures for a group to become a qualified party. The Montana Green Party now has 3,000 signatures. The deadline is March 15, 2018. Assuming the petition succeeds, it should be easy for the party to poll enough votes in November 2018 to remain on the ballot. Montana has three statewide races up in 2018, including Clerk of the Supreme Court, a partisan race in which voters don’t care very much who wins, so they are quite willing to vote for their favorite minor party.
The last time Clerk of the Supreme Court was up, in 2012, the Libertarian Party was in a two-way race with a Democrat, and the Libertarian nominee, Mike Fellows, received over 43% of the vote and carried a number of counties. Currently the Libertarian Party is the only qualified third party in Montana.