Senate Governmental Affairs Committee Chairman Joseph Lieberman said Friday that he couldn't remember the exact amount of campaign cash he'd accepted over the years from Citigroup, whose chairman Robert Rubin he has yet to call to testify before his Enrongate probe. During an interview with radio host Don Imus, the Connecticut Democrat acknowledged accepting $2,000 in contributions from Enron, prompting this exchange: IMUS: Well, what did you get from Citigroup? LIEBERMAN: More, but I couldn't tell you the amount. IMUS: Was it, like, $10,000? LIEBERMAN: Ah - I honestly don't know. I'd say it was.... IMUS: How about a million?...