A pair of interesting articles on the relationship between the Republican and Libertarian parties.   First, an OpEd by John Miller in the NYT titled "A Third Party on the Right" describes the effects of "fringe parties" in determining the outcomes of large, close elections.  

...George W. Bush is president today because of Ralph Nader, the Green Party candidate, whose liberal supporters almost certainly would have preferred Mr. Gore in a two-way race. In Florida, Mr. Nader attracted some 97,000 votes, dwarfing the 537-vote margin separating Mr. Bush from Mr. Gore.

There's a similar explanation for Mr. Thune's 524-vote loss: a Libertarian Party candidate, Kurt Evans, drew more than 3,000 votes. It marks the third consecutive election in which a Libertarian has cost the Republican Party a Senate seat. If there had been no Libertarian Senate candidates in recent years, Republicans would not have lost control of the chamber in 2001, and a filibuster-proof, 60-seat majority would likely be within reach.

While the "Green-Steal" of Gore's votes is relatively well documented in the press, the "Libertarian Problem" faced by the Republicans has not received as much attention and is consequently the focus of the OpEd.    Miller is very helpful in describing the differences & similarities between Libertarians & Republicans for NYT's core (left-wing) readership:

It's important to appreciate that Libertarian voters are not merely Republicans with an eccentric streak. Libertarians tend to support gay rights and open borders; they tend to oppose the drug war and hawkish foreign policies. Some of them wouldn't vote if they didn't have the Libertarian option.

But Libertarians are also free-market devotees who are generally closer to Republicans than to the Democrats. "Exit polling shows that we take twice as many votes from Republicans as from Democrats," said George Getz, a spokesman for the Libertarian Party.

Miller provides several examples of cases where the Libertarian vote count materially affected the outcome of several races to the detriment of the Republican party.  Unfortunately, the conclusion that Miller draws is spot-on and is very demonstrative of why the mathematically efficient long term result for Democracy is a 2 party system.   Libertarians, because they split the vote, are effectively "Democratic Party Operatives."

In response to Miller's article, Randy Barnett writes on How to Keep "Libertarians Inside the Tent."

What conservative Republicans often fail to realize is that libertarians are an important constituency that should not be ignored or taken for granted lest their votes be driven to the Libertarian party or even to the Democrats. Telling libertarians they should vote Republican despite their serious reservations about Republican policies is futile. These concerns need to be addressed rather than ignored.

A few of his key points:

• Recognize that Pro-Business and Pro-Markets are 2 separate things.  Far too many Republican economic strategies are actually the former
• Stand up for personal privacy & the Bill of Rights
• Apply Federalism more uniformly rather than simply raising it as a challenge to Democrat sponsored legislation (do that too!)