American support for same-sex marriage has declined to 65% from a peak of 71% in 2022 and 2023, according to a new Gallup poll released Wednesday, marking the first sustained drop after more than two decades of steady growth.

The decrease is driven primarily by changing views among Republicans, with only 37% now saying same-sex marriage should be legally valid, according to the survey conducted in May. Republican support for the moral acceptability of gay and lesbian relations also dropped to 35%. Democratic and independent views remained largely stable, with majorities in both groups supporting same-sex marriage rights.

The shift represents a notable change from the long-term trend that began in 1996, when only 27% of Americans supported legal same-sex marriage. Support grew steadily for decades, peaking at around 70% in recent years. Similarly, acceptance of same-sex relations as morally acceptable rose from about 40% in 2001 to a peak of 71% in 2022, before declining to 62% in the current poll.

Same-sex marriage has been legal nationwide since a 2015 Supreme Court ruling, and more than 800,000 same-sex couples were married as of last year, according to the Williams Institute at UCLA School of Law. However, political opposition persists, with lawmakers in at least 11 states introducing legislation in recent sessions calling for bans on same-sex marriage, though most measures have not advanced.

The poll also found declining acceptance of transgender issues, with about 40% of Americans viewing gender transition as morally acceptable, down from nearly 50% in 2021. This comes amid ongoing political debates over transgender rights, including restrictions on gender-affirming medical care for minors and participation in sports.

The Gallup poll was conducted May 1-17 among 1,001 U.S. adults and has a margin of error of plus or minus 4 percentage points.