On October 9, U.S. Senator Bernie Sanders endorsed all the Progressive Party member-nominees who are running for state office in Vermont, but only if they also have the Democratic nomination. He did not endorse any Progressive Party nominee who does not have the Democratic nomination as well.
Vermont permits aggregated fusion: candidates with the nomination of more than one party appear on the November ballot once, with both party labels following their names. The party listed first indicates that the candidate is a member of that party. Parties listed second are parties that nominated that same candidate, even though that candidate isn’t a member of the second-listed party.
The Progressive Party has 18 member-nominees on the ballot for state legislature. The Sanders endorsement includes twelve of them.