The Green Party is very new in New Brunswick. They have not contested a provincial election before.
They have some credibility in that their leader is disaffected Liberal Jack MacDougall who is well known in political circles for being an excellent campaign organizer.
MacDougall served as organizer for the federal Greens in the 2008 election which saw their share of the vote in New Brunswick climb from to 6.2% from 2.4% in 2006. How much of this has to do with MacDougall is impossible to tell but that 4.2 point increase compares favourably to the national climb of 2.3.
Opinion polls do not have the Greens coming in that high, instead ranging between 2 and 3% (of all voters) in a poll with a margin of error of +/- 3.4.
However, while third parties traditionally underperform their polling numbers because of weak organization, it could be said that the Greens may overperform their polling numbers because of strong organization. We'll have to see.
If the Greens did manage to replicate that 6.2% of the vote, they would still not be likely to win any seats. In fact, COR got 7.1% of the vote in 1995 and even with concentrated support and 6 incumbent MLAs on the ballot they couldn't get a seat.
When MacDougall sought the leadership of the Liberal Party in 2002, he won only 8% of delegates. However, he ran very strong in Saint John where he was active in business and community causes in the 1980s. He actually won a plurality of delegates in several Saint John ridings.
Had MacDougall run in a Saint John area riding, say Saint John-Fundy where long-time MacDougall ally Stuart Jamieson is stepping down, he may have had a shot. As it stands, I suspect he will place third (at best) in his chosen riding of Fredericton-Nashwaaksis.
The prospects for the Greens winning a seat are grim. However, if MacDougall gets into the leaders' debate... you never know. There a great many undecided voters and a great many disgruntled voters in this very unpredictable cycle. One never knows what might happen if an unknown leader of an unknown party were to catch on in a debate.
That said, I would give the chances of the Greens winning a seat 5-95.