Activists Pour Cash Into Voter Turnout

In a tight election where voter turnout could be crucial, a new force is sending people door to door to try to get conservatives to the polls.

Conservative groups, most notably Americans for Prosperity, are spending millions of dollars to ensure that as many supporters as possible cast a ballot. Their efforts, echoing voter drives by unions and other Democratic-leaning groups, represent a new X-factor in the presidential race. Many of the groups barely existed in 2008 and until now had largely focused their spending on television ads.