McCain was with his wife Cindy. In a break from tradition, he planned two final rallies on voting day - at an airplane hangar in Grand Junction, Colorado and later in Albuquerque, New Mexico. Both states went with President George W Bush in 2004, but polls have indicated that they are now leaning toward Obama.

If elected, McCain, 72, will be the oldest president ever to begin his first term.

Meanwhile, Republican vice-presidential candidate Sarah Palin went home to Alaska to vote and said she felt 'optimistic and confident.'

'I hope, I pray, I believe I'll be able to wake up as vice- presidential elect and work in transition mode with John McCain,' Palin told reporters, after initially slipping behind a red-white- and-blue curtain to vote. 'I'm exercising my right to privacy,' she joked.

She said Alaska was far removed from politics in Washington and what she would bring to the capital was 'good, healthy.'

'It's great to be home because forever I'll be Sarah from Alaska,' Palin said, after voting in Wasilla's City Hall, where she once served as mayor.

'I know it is a historical event, no matter which ticket prevails,' she said.

Palin said she hadn't yet spoken to McCain. She was scheduled to leave Alaska and join him in Phoenix on election night.