An angry and upset Rep. James Clyburn said Wednesday that his office has been deluged with nasty phone calls with racial overtones since his endorsement of Barack Obama a day earlier.

Clyburn told FOX News Radio's "Brian and the Judge" that the callers identified themselves as Hillary Clinton supporters. Clyburn, an African-American and the third ranking House Democrat, said a white intern in his office was so upset by the calls that she had to be consoled by other workers and left the office early.

"We got more vitriolic, nasty phone calls, really racially tinged phone calls in my congressional office, so much so, until one of the interns, a young lady who is not a stranger to politics ... and she is not a black person, she left the office, had to be consoled because of the kinds of phone calls from people who identified themselves as Hillary Clinton supporters," he said.

Clyburn said some of the callers used "names that I would not repeat on this show today."

"I was absolutely shocked, could not believe that this happened. I could understand people saying, 'Why are you doing this or why would you not support Hillary Clinton?' but to call me the kinds of names I have not heard since the '40s and '50s," he said.

Clyburn said some of the callers threatened to "sabotage this election." He added that he does not think Clinton understands her role in unifying the party.

"I’ve got a call in to Bob Johnson, a good buddy of mine, he’s a big supporter of Hillary Clinton, he’s now pushing for her to be on the ticket as VP. And I’m gonna tell him today they’d better really raise their voices because this kind of stuff is lethal," Clyburn said.

The House majority whip later told FOX News that the nomination of a black man as a major party presidential candidate demonstrates the distance the United States has come in a short term.

"I think historically it means in the 60th year since Strom Thurmond walked out of the party on the issue of race, our party has decided that it's time to turn the page on that issue in society," he said referring to the late Dixiecrat turned Republican senator who was later discovered to have fathered a child with a black woman who worked as the family maid.

But Clyburn tempered his enthusiasm for Obama's nomination, saying that there "are always pockets in this country of people who cannot find it in themselves to grow up. And to the extent which people fail to mature, we'll still have some work to do."