According to the KC Star's Prime Buzz blog:
Rep. Emanuel Cleaver of Missouri said Thursday that black Democratic superdelegates who support Sen. Hillary Clinton have been “bludgeoned verbally” to prod them to switch to Sen. Barack Obama.
Cleaver, who is African-American and a superdelegate, has backed Clinton since last summer and this week re-emphasized that support. He said that he himself has not been pressured, but that black superdelegates from all over the country have been subjected to harassment, threatened with primary opponents and called “Uncle Tom.”
He said they have been told, “You’re not black if you’re not supporting Barack Obama. ... It is ugly.”