Strong public support for same-sex marriage exceeds strong opposition by a significant margin for the first time in ABC News/Washington Post polls, and African-Americans have moved more in favor, perhaps taking their lead from Barack Obama on the issue.

Overall, 53 percent of Americans say gay marriage should be legal, steady the past year but up from 36 percent in just 2006. Thirty-nine percent "strongly" support it, while 32 percent are strongly opposed - the first time strong sentiment has tilted positive. Six years ago, by contrast, strong views on the issue were negative by a broad 27-point margin.

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Further, this poll, produced for ABC by Langer Research Associates, finds that support for gay marriage has reached a new high among African-Americans in ABC/Post polls, up from four in 10 in recent surveys to 59 percent now.

Another result shows increasing exposure: Seventy-one percent of Americans now say they have a friend, family member or acquaintance who's gay, up from 59 percent in 1998. People who know someone who's gay are 20 points more likely than others to support gay marriage.

Regardless of that shift, Obama's May 9 announcement of his support for gay marriage shows no measurable impact on political preferences. While more support than oppose his position, 51-41 percent, Americans divide on whether it's a political plus or minus, with most saying it's not a major factor in their vote choice.

SUPPORT - Support for gay marriage reached a majority for the first time in an ABC/Post poll in March 2011 and has held there since, at 51 to 53 percent. Strong support has been essentially at parity with strong opposition across that time, a shift from previous years.

In this poll, though, strong opposition to gay marriage is at a new low in polls since 2004, while strong support is at a numerical high, producing a 7-point positive gap.

Notably among groups, 59 percent of African-Americans in this survey express support for gay marriage - up from 41 percent in combined ABC/Post polls this spring and last summer. Likewise, 65 percent support Obama's new position on the issue. The National Association for the Advancement of Colored People announced its support for gay marriage last weekend.  

Fewer whites, 46 percent, approve of Obama's announcement, and 50 percent support gay marriage - numerically (albeit not statistically significantly) the fewest since 2010.

VOTE and GROUPS - While 20 percent see the issue as a major reason to support Obama, about as many, 23 percent, call it a major reason to oppose him, both among groups that look likely to have supported or opposed him anyway. Fifty-five percent say it's not a major factor.

Even among those who approve of the president's support for the issue, nearly six in 10 say it's not an important factor in their vote; 38 percent call it a major reason to support him. More of those who disapprove of his position, half, call it a major reason to oppose him in the election.

Sharp differences among groups persist. Republicans and conservatives oppose gay marriage by more than 2-1, evangelical white Protestants by more than 3-1. While Democrats support it by more than 2-1, the balance is tipped, as is often the case, by independents: Fifty-eight percent support legalizing gay marriage; 43 percent do so strongly.

Among other groups, support for gay marriage reaches 69 percent among adults under age 30 (with 51 percent "strong" support), compared with just 38 percent of seniors. (Half of seniors are strongly opposed). Support is also 14 points higher among college graduates than among non-graduates, 63 to 49 percent. But it's the same, 53 percent, among men and women alike.

FRIEND/FAMILY - As noted, seven in 10 Americans report having a friend, family member or acquaintance who is gay or lesbian. They're much more apt to support gay marriage (59 percent, vs. 39 percent of those who don't know someone who is gay) and also to approve of the president's position on the issue (56 percent, vs. 39 percent of others).

As with support for gay marriage, knowing someone who's gay is notably high among young adults and people with college degrees, 80 percent in each group. It's higher among women than men, 76 vs. 66 percent. Broad majorities of Democrats, Republicans and independents (65, 71 and 76 percent, respectively) also report having a friend, family member or acquaintance who is gay. It's 56 percent each, by contrast, among blacks and seniors.

STATE vs. FED - Obama said he supports gay marriage personally but believes the states should decide on its legality; on that the public splits about evenly, with 49 percent favoring state control vs. 46 percent who'd prefer to have the federal government make the rules.

Support for federal legislation is higher (57 percent) among proponents of gay marriage; among those who oppose gay marriage, the same share, 57 percent, prefer state rule. Thirty states have constitutionally banned gay marriage; eight (plus Washington, D.C.) have legalized it (including two in which those laws are yet to take effect).

Political divisions follow, with Republicans 23 points more apt to back state rather than federal rule, Democrats 14 points more likely to favor a single federal law - and independents roughly divided, 50-45 percent, state-federal.

METHODOLOGY - This ABC News/Washington Post poll was conducted by telephone May 17-20, 2012, among a random national sample of 1,004 adults, including landline and cell-phone-only respondents. Results have a margin of sampling error of 3.5 points for the full sample. 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.

Analysis by Damla Ergun and Gary Langer.