Via Arabist.net, here's an interesting cable, dated January 2008, from the U.S. Embassy in Baghdad. Titled "BLUEBLOOD SHIA CLERIC COMMENTS ON "BACKWARD" SADRISTS AND SISTANI'S FEARS AND FRUSTRATIONS," the cable describes a meeting with Emad Klanter, a member of a prominent clerical family in Najaf (my emphasis):
Son of a respected Najafi Ayatollah, nephew to Grand Ayatollah Ali al-Sistani, related by marriage to Muqtada al-Sadr, and bearing a faint resemblance to the actor Robert De Niro, Klanter is a direct descendant of the Prophet Muhammad but was not wearing the traditional Shia Sayyid's garb of black turban and cloak during our meeting at the IZ villa of Saad Jabr, a Saddam-era exile opposition financier and son of Iraq's first Shia Prime Minister.
It goes on to find Klanter, who calls the Sadrists "backward, almost like they are from a cave," fretting about will happen when U.S. troops leave. " Swinging his arms into an abbreviated 'Gator Chomp' type of gesture," the cable's author relays, "he said that if the U.S, leaves 'Iran will swallow us whole.'"
Or maybe Saudi Arabi will. Another interesting cable dated September 2009 and signed by former U.S. ambassador Christopher Hill paraphrases one interlocutor saying that "Saudi influence in Iraq was significant, perhaps more significant than Iran’s at the moment, given the financial and media assets at its disposal, and given Iran’s recent internal distractions."