“We always try to prepare for the worst,” said Oakland Police Separtment spokesman Jeff Thomason.

“This election is going to mark in history a change in the presidency: you''re going to have a woman in the presidency or an African American as president. I think everybody around here is voting for Obama, so if he gets in the White House everybody''s going to be happy. But, we’ll have our SWAT teams on standby and traffic teams here, so if something goes off we''ll organise and take care of the problem,” the 'Telegraph' quoted him as saying.

According to the paper, there have also been Internet rumours about plans for protests or civil disobedience by supporters of Democratic candidate Barack Obama if he was beaten by Republican rival John McCain in the forthcoming presidential poll.

Thomason said Oakland was prepared to deal with unrest as Oakland Raiders fans rioted in 2003 following their Super Bowl loss. Other cities that have experienced unrest include Detroit, Chicago and Philadelphia and are also planning to deploy extra officers on election day.

James Carville, a strategist for former President Bill Clinton and advisor to his wife Hillary''s 2008 presidential campaign, hinted Democrat supporters could be angry if Obama lost, given his lead in the polls.

“If Obama goes in and he has a consistent five-point lead and loses the election, it would be very, very, very dramatic out there,” Carville was quoted as saying.