The share of U.S. adults who support same-sex marriage and laws that protect LGBTQ people from discrimination has dipped in the last year, a survey has found.

After steadily increasing over the last decade, support for same-sex marriage dipped to 67% in 2023 from a record high of 69% the year before, according to the survey of more than 22,000 U.S. adults, which was conducted by the nonpartisan Public Religion Research Institute, or PRRI, and reported a margin of sampling error of 0.82%. More than three-quarters of those surveyed (76%) favored laws that protect LGBTQ people from discrimination in housing, employment and public accommodation, a decline from a record high of 80% in 2022.

Melissa Deckman, PRRI’s chief executive, noted that while support for same-sex marriage and nondiscrimination protections for LGBTQ people remains significantly higher than it was a decade ago, the year-over-year declines surprised researchers.

“You can’t really take a look at this report and not note some declines, especially among Republicans,” Deckman told NBC News in an interview. “Party polarization is really driving the national averages down.”

Democrats are much more likely than Republicans to support same-sex marriage, the survey found. Support among Democrats remained steady year-over-year at 82% in 2023, while Republican support dipped to 47% from 49% during that time period. Support for laws that prohibit discrimination against LGBTQ people took an even steeper hit among Republicans, dropping to 59% last year from 66% in 2022, while Democratic support remained steady at 89% in 2023.

A decline in support for same-sex marriage also appears to be driven by younger adults, or those ages 18-29, the survey found. Although a greater share of younger adults support same-sex marriage compared with older ones — and a greater share of younger adults identify as LGBTQ —  the share of young adults who supported same-sex marriage declined to 71% last year from 74% in 2022 and a record high of 79% in 2018.

“There’s been more of an emphasis on this idea that LGBTQ rights have gone too far in America — they’re hearing that in churches that are conservative, they’re seeing on social media that’s conservative, on far-right news sources that are conservative,” Deckman said, referring to those in the 18-29 age group. “And that message is resonating.”

Deckman noted that the drive in declining support from younger adults was not indicative of an increasing share of younger adults identifying as Republicans. 

Same-sex marriage was legalized across the U.S. in 2015 after a landmark Supreme Court ruling, Obergefell v. Hodges, determined that state bans against such unions were unconstitutional. Fears that the Supreme Court might overturn same-sex marriage rights have festered after Roe v. Wade was overturned in 2022. 

In December 2022, President Joe Biden signed the Respect for Marriage Act, which enshrined marriage rights for same-sex couples into federal law. However, that has not stopped state lawmakers from trying to chip away at the right. Just last month, Tennessee Gov. Bill Lee signed a law that will allow public officials in the state to refuse to perform marriages if doing so goes against their beliefs.

PRRI’s survey found that support for same-sex marriage is lower among respondents living in states where same-sex marriage would not be legal if Obergefell v. Hodges were overturned, 64%, compared with 72% in states where the unions would still be legal.

Republican state lawmakers across the country have pushed record numbers of anti-LGBTQ laws in legislatures in recent years. Last year, legislators introduced more than 500 such measures across the country, including 75 that became law, according to the American Civil Liberties Union. Many of the enacted laws restrict access to gender-affirming care for trans minors and limit trans athletes’ ability to participate on sports teams that correspond with their gender identities.

So far this year, conservative lawmakers have introduced more than 475 bills targeting the LGBTQ community, the ACLU found. The measures include those that would restrict bathroom use for transgender people and bar trans people from changing their sexes on their driver’s licenses.