NEWTON, Mass. — Joseph Kennedy III has launched his campaign for the Massachusetts congressional seat now held by retiring U.S. Rep. Barney Frank.

Kennedy today released a video announcement on his website before heading out on a campaign swing through the 4th Congressional District.

Kennedy started by greeting commuters at the Newton Center MBTA Station and talking to customers at a diner.

Kennedy is the son of former U.S. Rep. Joseph Kennedy II and a grandson of the late Robert F. Kennedy.