Although the next presidential primaries are still more than two years away, potential Republican nominees are already jockeying to earn favor with key constituencies. Our newly released 2013 American Values Survey: In Search of Libertarians in America finds that some key conservative constituencies, including libertarians, white evangelical Protestants and the Tea Party, are already identifying favorites among the slate of potential candidates. How influential each of these voting blocs will be in the candidate selection process will depend on their size, homogeneity, and engagement.

Of these conservative core voting blocs, Tea party voters are more engaged than any other group. More than 6-in-10 (62 percent) Americans who identify with the Tea Party movement say they always vote in primary elections, while white evangelical Protestants (48 percent) and libertarian voters (53 percent) vote in primaries at a rate comparable to Republicans overall (50 percent).

White evangelical Protestant voters make up a larger chunk (38 percent) of the Republican Party than do either libertarian voters (12 percent) or Tea Party voters (23 percent), but their voting power may be muted by both the higher participation rates of the other two groups, especially the Tea Party.

Finally, the extent that each voting bloc coalesces behind a single candidate will have a greater influence in deciding the eventual nominee.

White evangelical Protestant voters who identify or lean Republican currently have somewhat mixed candidate preferences. Based on a head-to-head question including several potential nominees, overall preferences do not differ substantially among Congressman Paul Ryan (19 percent), Governor Chris Christie (16 percent), former Governor Jeb Bush (15 percent) and Senator Marco Rubio (13 percent).

In contrast, some notable candidates are already rising to the top among libertarian and Tea Party voters. Among libertarian voters who identify or lean Republican, more than one-quarter (26 percent) say Paul would be their pick for 2016, followed by Senator Ted Cruz (18 percent) and Rubio (16 percent). And among the powerfully engaged Tea Party members who identify or lean Republican, Cruz has the lead (22 percent), followed by Rubio (18 percent) and Ryan (14 percent).

At this early stage, Paul retains an advantage among libertarian voters while Tea Party members, whose engagement could play an important role in deciding the nomination, prefer Cruz. The largest conservative constituency has yet to favor any one potential candidate, but remains important to watch given the significant impact white evangelical Protestants are likely to have on the nomination.