That's the argument made by one one major Clinton fund-raiser who will attend the dinner this evening. The fund-raiser said that the fact that Buffet is not endorsing Clinton (he is also helping Barack Obama) doesn't matter so much as long as he draws out the top donors as the second-quarter deadline approaches.

"We're not talking Tony Bennett here," said the fund-raiser, arguing that Buffet amounted to a "new breed of celebrity" who could attract more issue-oriented and wealthy donors.

"I don't know who he endorses," said the fund-raiser. "Obvious he is trying to be helpful, but I don't know if he endorses, period."