Biden placed a personal call to Harold Schaitberger, president of the International Association of Firefighters, early Friday morning to discuss his potential candidacy and a strategy to win, Schaitberger said.
News of the call was first reported by the Washington Post.
"You certainly came away with the view and feeling that he is moving toward seriously making a decision," Schaitberger said. He declined to speculate on timing of a decision or potential announcement.
"Our members and our union would very likely provide support to him and his candidacy," Schaitberger said of Biden.
The vice president has had a long personal affinity for firefighters and their national union.
When he ran for the Democratic nomination in 2007, Biden appealed to the IAFF, promising "if I'm the next president of the United States of America you will never have had any president that is more loyal and devoted to you than Joe Biden."
Biden often reflects on his deep personal connection to the firefighters, who helped respond to the tragic 1972 car accident that claimed the life of his first wife and young daughter. The first responders helped rescue Biden's two sons.