F. A. Hayek, writing in "The Constitution of Liberty," made the case that those who love liberty would do better trying to make inroads with progressives, rather than conservatives.
Conservatives, by definition, are tied to the traditional and resistant to new ideas. Conservatives in the U.S. tend to support smaller government because the U.S. has historically been a libertarian nation, not because they truly want people to be free to make their own decisions in life. Conservatives look to the past for guidance.
Progressives, on the other hand, look to the future. Although many have been deluded into supporting government programs as a way to improve society, their motivations (at least of the idealists, not the opportunists) are to seek the betterment of mankind. They are willing to try new ideas, and might be susceptible to a utilitarian argument showing the benefits of liberty.
That being said, the Republican Party is still a likely source of many libertarian voters, since many who value smaller government, free markets, and individual freedom have chosen it over the big government Democratic Party. Many of those natural libertarians call themselves fiscal conservatives, and are growing increasingly disenchanted with a Republican Party that continues to increase the size and power of government, despite all the talk about keeping the Democrats from doing the same.
