In pictures: US campaign trail

The two main contenders for the US presidency are involved in a final push for votes ahead of the election on Tuesday.

The Republican candidate, Senator John McCain, has embarked on a tour encompassing Pennsylvania, New Hampshire and Florida.

The Democratic nominee and front-runner, Senator Barack Obama, is attending rallies in Ohio.

In Wallingford, Pennsylvania, Mr McCain, who is trailing in the polls, urged supporters to "knock on doors - with your help we can win".

In a speech to a large crowd of supporters in Columbus, Ohio, Mr Obama urged voters to end "the politics that would divide a nation".

A BBC correspondent says the main priority for the parties now is to ensure that people who have already pledged their vote turn out on the day.

To this end, thousands of volunteers are making phone calls to registered voters, handing out brochures and knocking on household doors.

Some 130 million Americans are expected to cast a vote, in a higher turnout than in any election since 1960. Millions have already voted early.