I think the majority favors abortion nationwide based on their voter choice for many decades. Even Barry Goldwater was an abortion advocate.
December 2012: A Marist poll commissioned by the Knights of Columbus, titled “Abortion in America: Trends over Time”, finds that 10% of Americans believe abortion should be illegal in all cases; 12% say it should only be legal to save the life of the mother; 34% say it should be legal only in cases of rape or incest or to save the life of the mother; and 27% believe it should be legal – at most – in the first three months of pregnancy. Six percent say abortion should be legal in the first six months of pregnancy and 11% believe it should always be legal.
May 23, 2012: Gallup Poll says Americans self-identify as pro-life by a 50%-41% margin. 41% is the lowest “pro-choice” number since Gallup has been polling on this.
May 22, 2012: Gallup Poll finds that 51% of American adults believe that abortion is “morally wrong” and 38% believe that it is “morally acceptable.”
February 16, 2012: CNN: Americans Oppose Obama HHS Mandate 50-44 Percent (pdf)
January 21, 2012: Fox News Poll: Shows 50% of the public self-identifies as pro-life and 42% pro-choice. Fox notes that this is a near reversal of the figures from four years ago, when people identified themselves as pro-choice by a 51% to 40% margin.