Jessica Rinaldi for The Boston Globe via Getty Images

Nearly six in 10 Americans in a new ABC News/Washington Post poll oppose unilateral U.S. missile strikes against Syria, and even more oppose arming the Syrian rebels - a complication for Barack Obama and proponents of military action in Congress alike.

Even given the United States' assertion that the Syrian government used chemical weapons in the civil war there, 59 percent in the national survey, conducted Wednesday through Sunday, oppose U.S. missile strikes, far more than the 36 percent who support them.

See PDF with full results, charts and tables here.

Showing greater acceptance of allied action, attitudes move close to an even division on air strikes if other countries such as Great Britain and France participated - 46 percent in favor, 51 percent opposed. The U.K. House of Commons voted down military action last week, while France has signaled its willingness to participate.

At the same time this poll, produced for ABC by Langer Research Associates, finds that 70 percent oppose the United States and its allies supplying weapons to the Syrian rebels, underscoring the extent of public skepticism about U.S. involvement there.

A striking result is the lack of partisanship on the issue. Similar numbers of Democrats and Republicans alike oppose both unilateral U.S. air strikes and supplying arms to the opposition. And both groups divide closely on allied air strikes.

Public compunctions about involvement in Syria also are shown in strength of sentiment on the issue. Nearly four in 10 Americans, 39 percent, "strongly" oppose unilateral U.S. air strikes, vs. 18 percent who strongly support them. And the gap on arming Syrian rebels is even wider - 50 percent "strongly" opposed, vs. just 9 percent strongly in support.

The results to some extent reflect pre-existing attitudes; in an ABC/Post poll in December, 73 percent of Americans said the United States should not get involved in the situation in Syria. However, at that time, 63 percent said they'd favor military action if Syria used chemical weapons against its people. The new findings indicate a re-thinking of that view given the latest developments.

Attitudes can change with the course of events; it remains to be seen whether public views may be influenced by the ongoing debate in Congress, including support for Obama's call for force from some prominent Republicans yesterday and today. Nonetheless, current attitudes mark a battle ahead not just in Congress, but over public opinion more broadly.

GROUPS - As noted, opposition to unilateral U.S. air strikes is essentially the same among Democrats and Republicans, at 54 and 55 percent, respectively; it rises to 66 percent among political independents. It's essentially identical, as well, among ideological groups, ranging from 58 to 62 percent among conservatives, moderates and liberals alike. Large majorities across these groups also oppose arming the Syrian rebels, peaking, at 78 percent, among very conservatives.

Among other groups, while 54 percent of men oppose unilateral air strikes, opposition rises among women, to 65 percent - a customary finding in views on military action. On allied air strikes, opposition declines among both groups, but remains 10 percentage points higher among women.

Opposition to unilateral air strikes peaks among young adults, at 68 percent among those younger than 30. There's less of a pattern by age on allied strikes and on supplying arms.

METHODOLOGY - This ABC News/Washington Post poll was conducted by landline and cell phone Aug. 28-Sept. 1, 2013, in English and Spanish, among a random national sample of 1,012 adults. Results have a margin of sampling error of 3.5 points. The survey was produced for ABC News by Langer Research Associates of New York, N.Y., with sampling, data collection and tabulation by SSRS/Social Science Research Solutions of Media, Pa.