Bush made the declaration in front of about 40 people in attendance at the reception, according to the source.
Kathleen Hartington Kennedy Townsend, a former Maryland lieutenant governor and daughter of Robert F. Kennedy, first posted on Facebook Monday about the 41st president's apparent intentions to vote for Clinton, sharing a photo of herself and Bush, and writing, "The President told me he’s voting for Hillary!!"
Townsend later told Politico she met with Bush, 92, in Maine on Monday, where he told her about his preference in this year’s ballot. "That's what he said," she told Politico.
Townsend is a member of the advisory board of the Points of Light Foundation.