Mitt Romney is ahead by a single percentage point in Ohio, according to internal polling data provided to MailOnline by a Republican party source.
Internal campaign polling completed last night by campaign pollster Neil Newhouse has Romney three points up in New Hampshire, two points up in Iowa and dead level in Wisconsin and - most startlingly - Pennsylvania.
Internal poll show Romney trailing in Nevada, reflected in a consensus among senior advisers that Obama will probably win the state. Early voting in Nevada has shown very heavy turnout in the Democratic stronghold of Clark County and union organisation in the state is strong.
Romney is to campaign in Cleveland, Ohio and Pittsburgh, Pennsylvania on election day, reflecting the tightness of the race in Ohio and the tantalising prospect of success in Pennsylvania, which has not gone Republican in a presidential campaign for 24 years.
Nearly all public polling put Obama ahead in Ohio by whisker at least. The RealClearPolitics average of polls there gives the president a 2.8 per cent advantage. But the Romney campaign insists that pollsters have their models wrong and are overestimating Democratic turnout and underestimating Republican enthusiasm.
If the Romney campaign's internal numbers are correct - and nearly all independent pollsters have come up with a picture much more favourable for Obama - then the former Massachusetts governor will almost certainly be elected 45th U.S. President.
The most dramatic shift in the Romney campaign's internal polling has been in Wisconsin, which has moved from being eight points down to pulling level. President Barack Obama is campaigning in the state on the eve of election day.
Despite the Obama campaign's insistence that Romney's late decision to contest Pennsylvania is an act of 'desperation', former President Bill Clinton - Obama's most valuable ally on the stump - is holding four eve-of-election events there.