The Democratic and Republican parties are struggling to engage new voters in this year's presidential race, with an apparent deficit of enthusiasm suppressing the number of people who have registered to vote ahead of the 6 November election.

A Guardian survey of six of the most crucial swing states upon which the outcome of the presidential ballot is likely to depend has found that new voter registrations recorded between January and August this year are markedly down compared with the same period in 2008. The drop is particularly pronounced in several states for the Democrats – a likely indication that Barack Obama's re-election team has been unable to match the exceptional levels of voter excitement generated by his candidacy four years ago.