By Alex Dobuzinskis
LOS ANGELES (Reuters) - Fifty-three percent of Americans support making gay marriage legal, a Gallup poll showed on Friday, a marked reversal from just a year ago when an equal majority opposed same-sex matrimony.
The latest Gallup findings are in line with two earlier national polls this spring that show support for legally recognized gay marriage has, in recent months, gained a newfound majority among Americans.
Gallup said Democrats and political independents accounted for the entire shift in its survey compared to last year, when only 44 percent of all respondents favored gay marriage, while 53 percent were opposed. The percentage of Republicans favoring same-sex matrimony held steady at 28 percent.
Same-sex marriage remains a highly contested issue in U.S. politics, but homosexual couples have won the right to legally wed in five states -- Massachusetts, Connecticut, Vermont, New Hampshire and Iowa -- and the District of Columbia. Gay couples have faced setbacks elsewhere, and no statewide initiative to legalize gay marriage has ever won a majority vote.
The growing support for gay marriage comes after President Barack Obama signed into law legislation in December to repeal the ban on openly gay men and women serving in the military under a 17-year-old law known as "Don't Ask, Don't Tell."
Gallup noted the policy change, but said it was unclear if that influenced Americans' attitudes about same-sex unions.
"The trend toward marriage equality is undeniable -- and irreversible," Joe Solmonese, president of the gay rights group Human Rights Campaign, said in a statement.
Maggie Gallagher, chairman of the National Organization for Marriage, said the poll shows her fellow opponents of gay matrimony have been "shamed" into silence.
"Polls are becoming very sensitive to wording, and the wording being used in the media are not predicting accurately what happens at the actual polls when people vote," she said.
In a sign of a generation gap, Gallup found 70 percent of respondents between the ages of 18 and 34 support gay marriage, compared to only 39 percent among those 55 and older.
A Washington Post/ABC News poll in March showed 53 percent of Americans said same-sex marriage should be legal, and 51 percent said the same thing in a CNN Poll released in April.
By comparison, a 1996 Gallup found that 68 percent of Americans were opposed to same-sex marriage, a figure that has trended downward ever since.
Twenty-nine states have adopted constitutional amendments restricting marriage as between a man and a woman, and 12 other states have passed laws to that effect, according to the Human Rights Campaign.
In Minnesota, a proposal to put a constitutional amendment banning same-sex marriage before voters in 2012 gained momentum this month when it passed the state Senate.
In a setback for gays and lesbians seeking marriage rights, 52 percent of California voters approved a constitutional amendment that banned same-sex marriage in 2008, months after the state's Supreme Court had legalized it. Passage of the ban, known as Proposition 8, was seen as particularly significant because of Californians' history of supporting liberal causes.
In 2010, a federal judge found Prop 8 unconstitutional, but his decision was blocked by the 9th U.S. Circuit Court of Appeals while the case remains under judicial review.
(Reporting by Alex Dobuzinskis; Editing by Steve Gorman and Greg McCune)