Susan Carroll, the author of "Women Voters and the Gender Gap", states that the increase of women influence on political behaviors is due to four main categories: women outnumber men among voters; significant efforts are underway to increase registration and turnout among women; a gender gap is evident in the 2004 election as it has been in every presidential election since 1980; and women constitute a disproportionately large share of the undecided voters who will make their decision late in the campaign.