Another 10 percent surveyed in the poll volunteered they would prefer to outlaw abortion in the United States altogether or limit it earlier than 20 weeks after fertilization. At the same time, however, 54 percent say they oppose state laws that make it more difficult for abortion clinics to operate; compared to 45 percent who support such legislation. (See graphic below for a breakdown of results, and here for interactive polling data).

The findings come as lawmakers on Capitol Hill and in states across the country are pushing to ban abortions earlier and impose new requirements that make it harder for abortion clinics to operate. Under the Supreme Court’s 1973 Roe v. Wade decision abortions can be performed until the point when an individual doctor determines a fetus’s viability, which is generally defined as up to 24 weeks of gestation. After that point, the government can prohibit the procedure so long as it provides safeguards for the mother’s health and well-being.

The poll suggests that significant support exists for banning abortions earlier in a woman’s pregnancy, but far less for instituting onerous restrictions for abortion providers.

Bob Millsaps, an 80-year-old retiree in Bristol, Va., said he would ideally like to ban abortion except in cases of rape and incest, and prefers a 20-week ban to one starting at 24 weeks. But he added he opposes requirements, including one now in effect in Virginia, requiring abortion clinic operators to “upgrade the clinics to hospital standards. That’s forcing them to not having any abortions at all.”

More broadly, overall support for legal abortion remains stable, with 55 percent saying abortion should be legal in all or most cases, while 41 percent say it should be illegal in most or all cases. That finding is similar to a 2012 Post-ABC poll and surveys in recent years.

The poll was conducted July 18 to 21 among a random national sample of 1,002 adults. Results from the full poll have an error margin of 3.5 percentage points.

By more than a 2 to 1 margin — 66 to 30 percent — Americans say they prefer that abortion laws be decided for all states on the basis of the U.S. Constitution, rather than a state-by-state approach. This applies to both hardcore abortion rights supporters and opponents: 73 percent of those who say abortion should always be legal want a national rule, as do 72 percent of those who say it should be illegal in all cases.

But on a practical level the ground rules for abortion are being rewritten on the state level, where 50 new restrictions have been adopted since January, according to the nonprofit Guttmacher Institute. Earlier this month, for example, Texas Gov. Rick Perry (R) signed legislation into law that bans abortions after 20 weeks, requires physicians who perform abortions to have admitting privileges at a nearby hospital and requires all abortions take place in fully equipped surgical centers.

Such measures have cheered abortion opponents such as Nita Wallace, who lives in the Fort Worth area and has her own business. Wallace, who said she opposes the procedure because “God is the maker of life,” said religious Americans such as herself made a mistake in the past because “they didn’t get involved in politics so much, and now they’re realizing they lost ground by doing that.”

“What’s ground zero for making decisions? It used to be the Ten Commandments,” Wallace said, adding that media accounts have mislead the public into thinking abortion enjoys broad support. “I believe a lot of the American public, especially women, they have this idea that the majority of people embrace abortion.”

The Post-ABC survey reveals deep religious divisions. Two-thirds of white evangelical Protestants, 66 percent, believe abortion should be illegal in most or all cases, but an identical 66 percent of white non-evangelicals say it should be legal. Support for allowing abortion in most or all cases peaks at 73 percent among Americans with no religious affiliation, while Catholics divide about evenly – 50 percent legal, 45 percent illegal.

Six states have adopted laws banning abortion 20 weeks after fertilization or earlier;Sen. Marco Rubio (R-Fla.), a possible 2016 presidential contender, is considering introducing legislation to that effect in the Senate.

While the issue of abortion is a clear dividing line between Republican and Democratic Party leaders, it is less straightforward for many Americans.

Mark Whitt, who works for the county school system in Irvine, Ky., said he only supports abortion in order to save the mother’s life. Whitt said he was “a conservative Democrat, though they say there isn’t such a thing.”

Meanwhile a Columbus, Ohio, resident who asked that he only be identified by his first name, Robert, and described himself as “a conservative Republican” who backs abortion rights, said he did not understand why politicians were seeking to rewrite the nation’s abortion laws.

“I would really prefer that government focus on fiscal issues, and stay out of the social issues,” he said.

And Milo Shield, a professor at Augsburg College who lives in Prescott, Wis., said he also supports abortion access without restrictions until the 24th week of pregnancy. He questioned Wisconsin’s new law requiring hospital admitting privileges for abortion doctors, which Planned Parenthood said could shutter two of its four clinics in the state.

“There doesn’t seem to be data about whether it makes a difference to have a doctor present or hospital admitting privileges,” said Shield, who considers himself a libertarian and does not affiliate with either party. “I don’t know what Wisconsin’s rationale was. It’s like creationism — it’s shrouded in science, but not science-based.”

Regardless of their popular support, some of these new limits on abortion will facestiff legal challenges. In at least three instances — Arizona, Georgia and Idaho — federal and state judges have struck down abortion bans at 20 weeks after fertilization as unconstitutional (the Arizona ban was set at 18 weeks). On Monday a federal judge in North Dakota temporarily blocked the state’s law banning abortions as early as six weeks after fertilization, calling the legislation “clearly unconstitutional.”

Clement is a survey research analyst with Capital Insight, the independent polling group of Washington Post Media. Capital Insight pollster Jon Cohen contributed to this report.