Biden has said publicly he would make a decision at the end of the summer but the Times said the vice president and his associates were actively exploring getting in the race.

The Times, citing several people who have spoken with him and his advisers, said the Biden camp was contacting Democratic leaders and donors who have not firmly committed to Clinton, the clear leader among the five Democrats who have entered the race, or might be concerned about her prospects.

Times columnist Maureen Dowd also said Biden, 72, has been "having meetings at his Washington residence to explore the idea of taking on Hillary in Iowa and New Hampshire."

The paper said Steve Ricchetti, Biden's chief of staff, began talking to supporters in the months before Beau Biden died in May at age 46.

Dowd cited a conversation in which Beau Biden, a former attorney general of Delaware who was dying of brain cancer at the time, tried to get his father to promise he would run. The vice president's younger son, Hunter, also encouraged him, Dowd wrote.