In the closing moments of a segment on the June 19, 2007, episode of Hannity & Colmes, co-host Alan Colmes asserted, "Most Americans are pro-choice."
The truth? Well, it depends what poll you look at. In the specific issue of "pro-choice" vs. "pro-life," Colmes might want to take a look at a CNN/Opinion Research Corporation Poll from last month, May 4-6, 2007. 1,028 adults were questioned. The margin of error is ±3%. (source, scroll down)
"With respect to the abortion issue, would you consider yourself to be pro-choice or pro-life?"
Pro-choice 45% Pro-life 50% (Other answers comprised 5%)
To be fair, Gallup has been asking this exact same question for several years, and in a May 2007 survey, it has it 49% pro-choice and 45% pro-life (MoE ±3%). However, since August 2005, pro-life has been mostly trending upwards (and pro-choice always downwards) in the last three surveys.
PollingReport.com is a great place to peruse a lot of the different polls on this issue over the past few years.