Public attitudes have shifted against Edward Snowden, with more than half of Americans now supporting criminal charges against the former security contractor who's disclosed details of surveillance by the U.S. National Security Agency. And while most doubt that the NSA's efforts enhance security, most also don't see them as unjustified intrusions on privacy rights.

The public by 57-39 percent in a new ABC News/Washington Post poll also says it's more important for the government to investigate possible terrorist threats than for it to protect privacy rights - a substantial margin, albeit the narrowest in polls since 2002.

See PDF with full results and charts here.

A plurality thinks Snowden's disclosures have harmed national security (49 percent say so, 37 percent not, with the rest unsure). And 53 percent now support charging him with a crime, up from 43 percent last month, with a 13-point rise in "strong" support. People who think Snowden has harmed security are far more apt than others to favor criminal charges.

At the same time, this poll, produced for ABC by Langer Research Associates, finds that most oppose the idea of President Obama canceling his planned visit to Russia if that country were to give Snowden temporary asylum. More than half also oppose economic retaliation against any country that provides haven to Snowden. And Americans broadly reject a boycott on the 2014 Winter Olympics in Russia if it aids Snowden, as one U.S. senator, Republican Lindsey Graham of South Carolina, has suggested.

PRIVACY - Americans overwhelmingly think the NSA surveillance efforts intrude on some citizens' privacy rights - 74 percent say so - and about half, 49 percent, see the spying as an intrusion on their own personal privacy. In each case, though, some also see such intrusions as justified, 39 percent and 28 percent, respectively.

The net result is that 40 percent see the NSA activities not merely as intrusions on some Americans' privacy rights, but as unjustified intrusions. And 34 percent see the actions as unjustified intrusions on their own personal privacy.

In previous ABC/Post polls, in 2003 and 2006, fewer Americans saw federal anti-terrorism efforts as intruding on some Americans' privacy rights, and more said such intrusions were justified. As a result, the number who see unjustified intrusions now, while well short of a majority, is 10 percentage points higher than its previous peak, 30 percent in January 2006.

ARGUMENT - One challenge for the Obama administration is either to bolster its case that the surveillance is not intrusive, or that if it is intrusive, it's justified. Another is to back up the notion that it's worthwhile in the first place: Currently just 42 percent think the NSA's surveillance program is making the United States safer from terrorism. Forty-seven percent think it's not making much difference, and 5 percent say it's making things worse.

Then again, Snowden faces challenges of his own, beyond his now long-term tenancy at Moscow's Sheremetyevo Airport. As noted, whatever the utility of the NSA's activities, there's substantial public doubt that it carried out unjustified intrusions, and a plurality thinks Snowden's disclosures have hurt national security (though just 22 percent see "a great deal" of harm). "Strong" support for criminal charges has risen by 13 points since last month, to 36 percent. Only about half as many, 19 percent, strongly oppose such charges, down 8 points.

GROUPS - Views on the Snowden case largely bypass the usual partisan and ideological differences in U.S. politics; that's because of cross-pressures between customary partisan preferences on security (often emphasized by Republicans and conservatives) vs. views of the Obama administration (particularly supported by Democrats and liberals).

Instead there are differences by age, with younger adults more concerned about privacy rights and less apt to favor charging Snowden with a crime; and by gender, with women far more apt than men to support investigating terrorism threats over protecting privacy rights.

In terms of change from last month, shifts in favor of criminal charges against Snowden have occurred especially among women, middle-aged adults and strong conservatives.

Charging Snowden criminally is supported particularly by people who think that investigating terrorism trumps privacy; that NSA surveillance enhances U.S. security; that the NSA is not intruding on privacy rights, or if so, is acting justifiably; and that his disclosures have harmed national security. The last gap is the largest: Among those who see no damage to security, just 33 percent support criminal charges against Snowden. But among people who think his disclosures have harmed national security, 71 percent say he should be charged with a crime.

METHODOLOGY - This ABC News/Washington Post poll was conducted by telephone July 18-21, 2013, in English and Spanish, among a random national sample of 1,002 adults, including landline and cell-phone-only respondents. Results have a margin of sampling error of 3.5 points, including design effect.

The survey was produced for ABC News by Langer Research Associates of New York, N.Y., with sampling, data collection and tabulation by Abt-SRBI of New York, N.Y.