Cantwell challenger from her left -- just what some Democrats wanted

It seems that leftist ex-Black Panther Party member Aaron Dixon is running for the US Senate as a Green this November against incumbent Democrat Maria Cantwell. This gives those liberals who complain about Cantwell's somewhat rare moderation a protest candidate, and this arguably helps Republican challenger Mike McGavick should it be a close enough race (consequently, he needs to close the gap in polls before I'll buy that this entry means anything).

I'm curious if the entry of Dixon will force a primary against previously announced Green Party candidate Bern Haggerty, or if Haggerty will simply run for something else. Since the Greens don't have major party status in the state, it must be decided in some sort of party convention setting.