Rick Santorum in The New York Times 2010s

On Civil Rights: I would never attend a same-sex wedding

The more conservative members of this Republican field--among them Cruz; Santorum; and Bobby Jindal--have aggressively emphasized their opposition to same-sex marriage. For them, the issue can be used to differentiate themselves not just from Democrats but from mainstream Republicans, like Jeb Bush, who is trying to appeal to a broader audience with an eye to the general election.

Support for same-sex marriage is increasing among Republican voters, but it is still a minority view. That creates a split between conservative Republicans looking to win a primary, and candidates seeking to win a primary without carrying too much baggage into a general election.