The Republican Party, broadly speaking, is comprised of many factions that are often at odds with one another. Prominent examples are the battles between the grassroots and the national party establishment and between defense hawks and non-interventionists.
Perhaps fiercer than any of these fights is the long-standing conflict between social conservatives and libertarians. But when the Supreme Court legalized same-sex marriage last month, they created an opening for a wedding between these two groups, which could benefit the Republican Party ahead of the 2016 election.
To be clear, libertarians come in many stripes. There are those who reject the political system, those who ally themselves with the Libertarian Party itself, some who are working to change the Republican Party from within, and those who would only consider voting for a Republican candidate under certain circumstances.
Historically, during the Cold War, the common enemy of communism helped foster unity among libertarians and conservatives. Once the Soviet Union collapsed, however, this unifying purpose went away.