As a self-described political conservative, Reagan Larson might seem to be a natural fit for the Republican Party. The 19-year-old college student from South Dakota grew up in a Catholic household that objected to same-sex marriage, and she remains firmly opposed to abortion.

But in many ways, that is where the ideological similarities end. Ms. Larson, a dual major in biology and Spanish at Gustavus Adolphus College in St. Peter, Minn., does not oppose the legalization of marriage equality. She views climate change as undeniable, believes “immigrants make our country richer,” and disagrees with her parents on the need for a border wall.

Ms. Larson is part of Generation Z, one of the most ethnically diverse and progressive age groups in American history. People born after 1996 tend to espouse similar views to the age cohort just ahead of them, the Millennials, but they are far more open to social change than older generations have been, according to the findings of a new report by the Pew Research Center. The findings mark a shift that could substantially reshape the nation’s political and economic landscape.

Democrats of all ages tend to align fairly closely on major social and political issues, but the report highlights a sharp generational divide among Republicans. For example, more than half of the youngest Republicans surveyed said that racial and ethnic diversity was good for American society, a view shared by fewer than 40 percent of their Millennial counterparts, 34 percent of Generation Xers and just three in 10 baby boomers.

Young Republicans are also more likely to approve of same-sex marriage and accept transgender people.

Each succeeding generation of Americans tends to be more progressive than those that came before, Ms. Bennion noted, a trend that potentially poses a long-term threat to the Republican Party’s power.

“If there isn’t a will to change within the party,” she said, “it could become permanently in the minority moving forward.”