Kennedy's ex-environmental colleagues sign letter urging him to drop White House bid The HillRFK Jr.'s onetime allies in environmental advocacy call for him to drop out CNN'The Five': Biden is concerned about RFK Jr. — and it shows Fox NewsKennedy family members' Biden endorsement is a blow to RFK Jr. MSNBCR.F.K. Jr.'s Environmental Colleagues Urge Him to Drop Presidential Bid The New York Times