The poll, conducted by telephone from June 20 to 24, found that just over half, or 52%, of Americans said abortion should be legal in all or most cases, down from 59% in January, Reuters reported.
Forty-three percent said it should be illegal in all or most cases, the highest number since the poll started asking the question in 1995. The January poll found 39% opposed in all or most cases.
Religious beliefs or affiliation played a large role in respondents´ views on abortion, the poll found, with 63% of evangelical white Protestants saying it should be illegal in all or most cases and 35% favoring a ban in all cases. But two-thirds of non-evangelical white Protestants said it should be generally legal.
Catholics mirrored the public at large in their views, with 55% saying it should generally be legal.
Support for legal abortion has averaged 56% in a dozen polls in the past five years, with opposition at 41%.
The poll of 1,022 adults drawn from a random national sample had a margin of error of plus or minus 3 percentage points.