A new poll shows opposition to gay marriage plummeted 6 points from last year's survey, leaving fewer than half of those polled in opposition to its legalization.

The survey, which was conducted from July to September and was released Wednesday by the Pew Research Center, found that forty-two percent of Americans say they favor gay marriage, while 48 percent oppose it. In 2009, 54 percent of respondents opposed, while 37 favored, legalizing the institution.

Also for the first time, majorities in two religious groups – white mainline Protestants and white Catholics – favor gay marriage. Fifty-three percent of Democrats support its legalization, while just 24 percent of Republicans do.

β€œThe shift in opinion on same-sex marriage has been broad-based, occurring across many demographic, political and religious groups,” the poll's authors wrote.

Two other nationwide polls this year have found a narrow majority of Americans in support of gay marriage. Fifty-two percent of respondents to an AP poll released last month support its legalization, while a CNN poll released in August also turned up a slim majority in favor (50.5%).