NEW YORK – Though Barack Obama and Mitt Romney rarely tackle the topic of abortion head-on, the void is being filled by rival advocacy groups targeting swing states with ads depicting one or the other candidate as an extremist in his stance on the divisive issue.

Obama, according to the National Right to Life Committee, is "the most pro-abortion president this country has ever seen." Another anti-abortion group, the Susan B. Anthony List, is running anti-Obama TV ads titled "Abortion Radical."

From the other side, groups supporting legal access to abortion, as well as the Obama campaign itself, depict Romney and his running mate, Rep. Paul Ryan, as eager to ban most abortions as part of a Republican "war on women." The GOP ticket "is extremely dangerous to women's health," says Nancy Keenan, president of NARAL Pro-Choice America.