President George W. Bush evoked the September 11th, 2001, attacks today in an emotional appeal for support in a tight White House race, but Democratic rival Mr John Kerry told voters America needed a fresh start after Mr Bush's "catastrophic mismanagement."
Mr Bush and Mr Kerry hunted for votes in the crucial swing states of Florida, New Hampshire and Ohio as polls showed them running close four days before the election.
A Reuters/Zogbytracking poll found them tied at 47 per cent and other surveys showed the race a dead heat or gave Mr Bush only a slight edge.
Mr Bush was expected to get a campaign-trail boost later on Friday from California Govenor Arnold Schwarzenegger, while rock legend Bruce Springsteen planned to join Kerry on the campaign trail for the second consecutive day.
Both campaigns searched frantically for new opportunities in the battle to accumulate the 270 electoral votes needed to win, with the Democratic bastion of Hawaii getting attention after polls showed a tight race there.
Vice President Mr Dick Cheney will head to Hawaii on Sunday to make a play for the state's four electoral votes, while former Vice President Mr Al Gore - who carried the state easily against Mr Bush in 2000 - and Mr Kerry's daughter Alexandra were already there.
Mr Bush began the day in New Hampshire, which he narrowly carried in 2000, where he was joined by relatives of Americans killed in the September 11th attacks.
Polls show Mr Bush's leadership in the war on terror is his strongest selling point, and in a somber speech he reminded supporters of the attacks and the threats still faced by the United States.
"As we fight the terrorists, they will try to frighten us, they will test our will with their barbaric tactics. We must be resolved. So long as I am your president, we will not be held captive by fear," Mr Bush said in Manchester, New Hampshire.
"As long as I am the president, we will be determined and steadfast and we will keep the terrorists on the run," he said, reminding voters that since the attacks in Washington and New York, "we've been through a lot together."
"The issues vary, the challenges are different every day, the polls go up, the polls go down, but a president's convictions must be consistent and true," he said.
Mr Kerry, barnstorming across Florida, criticized Mr Bush's handling of the Iraq war and his failure to capture al Qaeda leader Osama bin Laden, saying it left the United States more vulnerable to attacks.