But views can evolve; baby boomers, who supported big government in their 20s and 30s, have become more conservative over time, the Pew center has found. While today’s young voters are more likely to identify as Democrats than Republicans or independents, their ideas and philosophies are not quite fixed yet, said John Della Volpe, the polling director at Harvard’s Institute of Politics. Here in Missoula, young people who voted for Mr. Obama last year said in interviews that they would be open to voting Republican, particularly if a candidate supports same-sex marriage. Young Republicans, too, hope their party will shift on that issue. “The social issues are hard,” said Ashley Nerbovig, a 19-year-old who backed Mr. Romney. “It’s not realistic that you can be against gay marriage and abortion.” If the economy had been in better shape, she said, “I would have picked Obama over Romney for social issues.”