New York Times:

For most of the last two decades, a clear majority of Americans has supported the right to abortion. A new poll, though, shows that support for abortion has declined, with the public almost evenly divided over the issue.
The shift has occurred in just the last year. In 2008, a poll conducted by the Pew Research Center found that those in favor of keeping abortion legal outnumbered opponents by 54 to 40 percent. The new poll, also conducted by Pew researchers, and released on Thursday, showed that the gap had narrowed considerably: 47 percent of those surveyed said abortion should be legal in all or most cases, and 45 percent said it should be illegal in all or most cases — a difference within the poll’s margin of sampling error.
The new survey did not find the reasons for the shift in opinion. But Pew researchers pointed out that it has occurred since the election of President Obama, a Democrat who supports abortion rights but has often spoken about the need to reduce the number of abortions.