Randy Barnett thinks so:
In hindsight, I think that the creation of the Libertarian Party has
been very detrimental to the political influence of libertarians. Some
voters (not many lately) and, more importantly, those libertarians who
are interested in engaging in political activism (which does not
include me) have been drained from both political parties, rendering
both parties less libertarian at the margin.
Put another way, in proportional voting parliamentary systems, there
are many political parties and governments are often formed by
organizing a coalition in which they must cater to smaller parties,
especially when holding a only slim parliamentary majority. In a
winner-take-all first-past-the-post electoral system--like we have in
elections for both Congress and the presidency--the major parties are
each themselves coalitions of political interests. To win an election,
they need to gather a coalition of voters to get over 50% of the vote,
so the marginal voters become important to them. Of course, they cannot
make efforts to reach marginal voters that completely alienate their
"base" (which is one the problems facing Democrats at the moment).
While some libertarian political activists are certainly Republicans
and Democrats, the existence of the Libertarian Party ensures that
there are fewer activists and fewer voters in each major party
coalition than would otherwise exist. Therefore, each party's coalition
becomes less libertarian. I do not mean to exaggerate the extent of
this effect. But even a handful of political activists in local and
state party organizations can make a big difference. Whatever one
thinks of the initial creation of the Libertarian Party, its continued
existence seems to be a mistake for libertarians.
While I agree that the LP has been bad for libertarianism, I disagree with Barnett's thesis. I have no problem with political activism, yet I don't see libertarianism gaining strength by becoming yet another voting bloc within the Republican and Democratic parties. Both parties are devoid of a philosophy (unless you consider ruling one), and allaying with them will do little but corrupt. As long as we're looked at like aliens at dinner parties, libertarianism will languish in the political basement.