U.S. Justice Department Foreign Agents Registration Act records submitted by Black's firm describe lobbying efforts during the 1980s on behalf of brutal Angolan guerrilla leader Jonas Savimbi, who was fighting the country's Marxist government, The Washington Post reported Thursday.

Black's firm also represented other U.S.-backed leaders with dismal human rights records, including Philippine's Ferdinand Marcos, Zaire's Mobutu Sese Seko, Nigerian Gen. Ibrahim Babangida and Somali President Mohamed Siad Barre.

Democrats say they want the presumptive Republican presidential nominee to fire Black because of his client list.

McCain, R-Ariz., "portrays himself as Mr. Clean, and then he has all these lobbyists around him who are connected to a lot of not-so-clean people," said Paul Light, a public service professor at New York University.

Sen. Barack Obama, D-Ill., can paint McCain as a Washington insider, Light told the Post, "and what could be more Washington-esque than having a dictator as a client?"

Republicans counter that Obama's hands aren't clean. They note that while Obama doesn't accept donations from lobbyists, the senator has had lobbyists informally advising him.