The highly-anticipated show, starring Holmes as Jackie Kennedy, was cancelled last week (ends09Jan11) by History Channel bosses who felt the final product was "not a fit" for the network.
New reports suggest it was scrapped after "intense" pressure from the clan, including Caroline Kennedy - the only surviving child of John F. Kennedy and Jackie Kennedy.
According to the Hollywood Reporter, Caroline, along with Arnold Schwarzenegger's wife Maria Shriver, the daughter of Eunice Kennedy Shriver, fought to have the project "killed".
Family members are said to have been upset over Greg Kinnear's depiction of JFK as sex-crazed and the portrayal of Joe Kennedy as power-hungry.
A senior History Channel source tells Britain's The Times newspaper the report is "100 per cent true".