"If anybody ever tells you that one vote doesn't count, you tell them to come talk to me," Gore said at a stop in Jacksonville, where black leaders charged that thousands of votes were discarded four years ago.

Gore lost the presidential election to President George W. Bush in 2000 by only 537 votes in Florida after the US Supreme Court decided to stop vote recounts in several counties.

Gore urged African-American voters to turn their anger into energy at the polls. "Turn all of that energy and all of these feelings into a nonstop effort between now and the time the polls close at 7 p.m. on November 2," he said.

Florida is one of a few key states where polls show Bush and Kerry are locked in a dead heat. Bush campaigned in the state Saturday, and Kerry campaigned there on Sunday.

Meanwhile, former president Bill Clinton will return to the campaign trail on behalf of Kerry on Monday, six weeks after he underwent heart surgery to bypass blocked arteries, officials of the Democrat Party said Sunday.