The commission is said to be similar to panels that investigated the 1986 space shuttle Challenger disaster and the nuclear power plant accident at Three Mile Island in 1979. The person spoke on condition of anonymity ahead of a public announcement.
Graham served in the Senate from 1987 to 2005 and previously served two terms as Florida governor.
"The commission's inquiry will range from the causes of the spill to the safety of offshore oil drilling and the functioning of the Minerals Management Service, the government agency that grants drilling rights."
Enviros welcomed the news: "Bob Graham has been a longtime ally in the fight against drilling," said Mark Ferrulo, executive director of Progress Florida. "He'll make the watchdog a dog and not a puppy."