Ross Tilchin writes up the results of a Brookings study on libertarians in the Republican Party, citing some of the research I have done here on Pileus. The main point Tilchin argues is that libertarians are at a severe disadvantage nationally within the Republican Party, relative to competing constituencies like moderates and the religious right. However, see also David Kirby’s rejoinder at Cato@Liberty. He argues that the Brookings study seriously underestimates the proportion of libertarians in the general population and in the Republican Party. The debate seems to turn on how strictly one wants to operationalize the concept “libertarian.” If weak libertarians are included, there are many more of them. Regardless, I echo Kirby’s appreciation of growing scholarly attention to the political role of libertarians in the U.S. polity.
For more on figuring out where libertarians are, also check out an interesting paper on two-dimensional ideological preferences at the congressional district level by Warshaw and Rodden. (Americanideologyproject.com is an interesting site for data on one-dimensional preferences at the subnational level in the U.S.)
PILEUS 
Jason,
Do you know if there’s a publicly available version of Warshaw and Rodden’s dataset? I’m curious which districts are which on their maps and charts.
I’m also curious if they did a follow up on which districts were more or less likely to flip in the 2010 election.
I don’t think they make those data publicly available. The paper later transmogrified into something about measuring individual issue opinions at the local level: http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8484451