NEW YORK (AP) — Americans, regardless of generation, are deeply conflicted as they wrestle with the legality and morality of abortion, with a substantial majority identifying themselves as both “pro-choice” and “pro-life,” according to a sweeping new survey.

While a solid majority — 56 percent — says abortion should be legal in most or all cases, 52 percent say abortion is morally wrong.

The detailed and nuanced findings were released Thursday by the Public Religion Research Institute, based on a survey of 3,000 adults — one of the largest ever to focus on Americans’ views of abortion.

The survey devoted particular attention to the views of young adults. It noted that 18-to-29-year-olds are far more likely than their elders to support same-sex marriage, but found there is no comparable generation gap regarding abortion.

In addition to its many new findings, the survey tracked other polls over the past 12 years to highlight a sharp discrepancy in attitudes toward the two most prominent hot-button issues of the culture wars.

Views on abortion have been stable, with 56 percent of Americans telling Gallup pollsters this year that it should be legal in most or all cases compared to 57 percent who said that in 1999. In contrast, support for same-sex marriage has surged — from 35 percent in 1999 to 53 percent in 2011, according to Pew Research Center polls.

A key factor in that discrepancy relates to attitudes of the so-called millennials between the ages of 18 and 29.

“Millennials strongly support gender equality and rights for gay and lesbian people,” the survey said. “However ... younger Americans are no more supportive of abortion rights than the general population.”

For example, 57 percent of millennials favor same-sex marriage, compared to 32 percent of baby boomers aged 50 to 64. Yet when asked about abortion, support for legal abortions was virtually the same — 60 percent among millennials, 59 percent among boomers.

Ambivalence was reflected in other responses from millennials: 68 percent said legal abortions should be available from health professionals in their community, while only 46 percent said having an abortion is morally acceptable.

The Public Religion Research Institute, which conducted the survey with funding from the Ford Foundation, is a nonprofit, nonpartisan organization which studies the intersection of religion and public life. Its CEO, Robert P. Jones, said both sides of the abortion debate were likely to find a mix of encouraging and discouraging findings in the new survey.

“At the end of the day, Americans are committed to the availability of abortion, and conflicted about its morality,” he said in an interview. “I would call it a stable tension.”

One notable finding pertains to the labels “pro-choice” and “pro-life” — which are widely used by rival advocacy groups and are presented as either/or choices in most polls.

In the new survey, 70 percent of respondents said the term “pro-choice” describes them somewhat or very well, and nearly two-thirds similarly embraced the term “pro-life.”

Nineteen percent said abortion should be legal in all cases and 37 percent said it should be legal in most cases. Fourteen percent said it should be illegal in all cases; 26 percent said it should be illegal in most cases.

With the exception of white evangelical Protestants, majorities of major religious groups — including Roman Catholics — favor legalized abortion, according to the survey. Only 29 percent of white evangelicals said abortion should be legal in most or all cases.

The findings reflect a “decoupling” of the debates over abortion and same-sex marriage, according to Jones, who predicted the two issues “will increasingly go forward on their own tracks.”

He noted that focus groups of millennials convened as part of the survey tended to depict same-sex marriage — but not abortion — in positive terms.

“Abortion is just a different kind of issue, even for those who support it,” Jones said. “It’s not the kind of issue that one celebrates.”

The findings mesh with recent commentary by some conservative leaders, who feel they can compete vigorously for the backing of young people on abortion issues but acknowledge setbacks in opposing same-sex marriage.

“We’re losing on that one, especially among the 20- and 30-somethings,” said Jim Daly, president of Focus on the Family, in a recent interview with World Magazine. “I don’t know if that’s going to change with a little more age — demographers would say probably not.”

Leslie Kantor, national director of education for the Planned Parenthood Federation of America, said the surge of young adults’ support for same-sex marriage could be explained by the fast pace of gay-rights political change and by the prevalence of gay characters and celebrities on TV and in other media.

“For young adults, the vast majority know someone in their life who is gay,” Kantor said. “There’s no comparable coming out process related to abortion — even though by age 45 one-third of American women will have had one.”

Angela Ferrell-Zabala, who does abortion-rights outreach on college campuses for the Religious Coalition for Reproductive Choice, said young adults’ attitudes may be affected somewhat by campaigns depicting abortion as shameful.

But as many legislatures toughen state restrictions on abortion, she contends there are signs of an abortion-rights backlash.

“I’m seeing young people reaching out, who are outraged by these attacks,” she said.

The survey was based on telephone interviews conducted between April 22 and May 8 among a random sample of 3,000 adults in the continental United States, including 750 who were interviewed on cell phones. The margin of error for the full sample is plus or minus 2 percentage points, and higher for subgroups.