Support for abortion rights has slipped in America this year and now barely edges opposition, while the issue's importance has fallen, according to a new survey released on Thursday.

Barack Obama's election as president may have contributed to both trends. It has reassured Democrats that abortion rights are secure.

The findings by the nonpartisan Pew Research Center come as the polarizing issue has been injected in the debate around reforming health care, which is Obama's top domestic priority.

In polls in 2007 and 2008, supporters of legal abortion clearly outnumbered opponents. Now ... there have been modest increases in the numbers who favor reducing abortions or making them harder to obtain, the organization said.

In 2007 and 2008 Pew found that supporters of abortion rights outnumbered those saying it should be illegal in most or all cases by 54 to 40 percent.

This year, two surveys of 5,500 adults found 47 percent supporting legal abortion with 44 percent opposed.

Obama is a strong supporter of abortion rights.

The pattern of changes suggests that the election of a pro-choice Democrat for president may be a contributing factor, the polling organization said.

The poll found that only 15 percent of respondents thought abortion was a critical issue, down from 28 percent in 2006. Among liberal Democrats, only eight percent viewed it as critical, down from 34 percent in 2006.

Even among conservative Republicans this number had dropped to 26 percent from 35 percent.

The importance of social issues in voters' minds normally falls during economic hard times.

Some conservatives have argued claim that Obama's healthcare plan will provide federal funding for abortion, an allegation the president has denied.