'Walmart moms': The women who could decide which man wins
In previous US elections the campaigns have courted soccer moms and hockey moms in suburban America as part of their strategy for winning the White House.
In 2012, the pollsters say the key demographic will be the so-called Walmart moms - busy women on a budget who come to the giant retailer for cost and no-frills convenience.
President Barack Obama currently enjoys a nine-point advantage among women in an average of polls, but that lead has dropped in recent days. It is also countered by Mr Romney holding a similar lead among men.
Both candidates have courted women voters aggressively, particularly in swing states like Colorado where there are 100,000 more women than men registered to vote.
The BBC's Steve Kingstone went to Denver to meet Rebecca Griego, a single mother with three teenage daughters, and Catherine Jones, who lost her job and is now a stay-at-home mother looking after a three-year-old daughter.
Produced by the BBC's Rozalia Hristova, Andrew Herbert and Bill McKenna.