“I think it was very much a generational difference, too,” he said later, adding a warning to Republicans: “They need to start embracing libertarian issues or it’s going to start really hurting them in elections.”

He said it was time for social conservatives to recognize a shifting society. “People can be socially conservative in their private activities without trying to impose their views on other people,” said Mr. McCobin, who leads Students for Liberty.

What is striking is that even some young social conservatives who do not want their party to abandon its platform on culture say Republicans would de-emphasize those issues. Anna Page, 19, a Wellesley freshman attending CPAC, said support for same-sex marriage was now a matter of “pure statistics” among millennials.

“If the party wants to move forward and appeal to our generation they have to appeal to the majority to succeed,” Ms. Page said.

Zach Pohl, an Ohio State junior who was strolling through CPAC wearing a Russian-style winter hat with “OBAMA” and the Soviet hammer and sickle emblazoned on it, said he was not really moved by the same-sex marriage issue.

“Religiously, I don’t agree with it, but at the same time I don’t really care,” Mr. Pohl said.

Leading social conservatives worry about the rise of libertarianism or apathy on social issues in the ranks of young Republicans. Former Senator Rick Santorum of Pennsylvania, a cultural conservative, acknowledged that libertarian social views were no longer confined to free-spirited college Republicans, but were taking root among conservatives in their 30s and 40s.

Mr. Santorum said that after he speaks to youthful audiences, they give him feedback about how they had not previously heard his case about the importance of cultural conservatism as it relates to the centrality of the family.