Ballot Access News - Maine requires a group that wishes to be a ballot-qualified party to have at least 5,000 registered members by December 1 of the odd year before an election year. The only group that tried to use this procedure for 2016 is the Libertarian Party, which has been registering members all during 2015. The party has submitted 6,482 voter registration cards. The state will say on or before December 8 whether the party has enough registered members.
The Green Party is also ballot-qualified in Maine. It got that status by using the independent candidate procedure to place its gubernatorial nominee on the November ballot and then polling over 5% for Governor. The first time the Green Party did that was in 1994, when Jonathan Carter got 6.4%.
The only other time the Libertarian Party was a ballot-qualified party in Maine was in 1991 and 1992. It got that status by having an independent candidate poll over 5% for Governor.