In the US Congress, there are leadership positions held in both majority and minority parties (e.g. the "majority leader" or "minority whip"). In practice, there are almost always two parties, so the "minority" party is simply the one that isn't the majority party. At present, this means either the Republican or Democrat party is the minority.
However, there are periods of time during which a third party grows in influence (typically leading to one of the two dominant parties dying off), and even at present there are a number of "independent" candidates associated with, e.g. the Libertarian, Green, etc. parties.
How do those third parties factor in to the "leader/whip" heirarchy? Is there a Libertarian party leader and whip in Congress, and do those positions grant any official responsibilities or benefits to the people that hold them?