CHARLOTTE, N.C. — Matt Hoagland, the county leader of a group of young North Carolina Republicans, is busy trying to ramp up enthusiasm for Mitt Romney at the grass-roots level. So there are a few things he avoids mentioning to prospective young voters he wants to woo, including the hot-button topics like abortion and same-sex marriage, which have dominated campaigns past.

“Social issues are far down the priorities list, and I think that’s the trend,” Mr. Hoagland, 27, said. “That’s where it needs to go if the Republican Party is going to be successful.”