The candidates converged on Madison from around the state. They support liberal causes such as civil unions and legalizing marijuana, but - like conservatives -also hope to move power from the federal government to "as local a level as possible," said Bob Burke, the party's candidate for governor.
Libertarians make up the bulk of this year's third-party candidates on Wisconsin ballots. Unlikely to win, outside candidates can shape races by forcing candidates from the two main parties to shift right or left. They also can draw enough votes from Republicans and Democrats in close races to hand victories to candidates who might not have prevailed in two-way races.
That happened in 2002, when Libertarian Ed Thompson received 10 percent of the vote, hurting Republican Scott McCallum who lost to Democratic Gov. Jim Doyle by less than 4 percent. The same thing could happen this year, with the latest poll showing Republican Gov. Scott Walker and Democratic challenger Mary Burke in a dead heat.
"For Walker and Burke, every vote they lose to a third party is a vote that might make the difference," said Mordecai Lee, a political science professor at the University of Wisconsin-Milwaukee.
An Associated Press review of general election results for statewide offices and the Wisconsin Legislature found third-party candidates have received enough votes to sway Wisconsin races six times since 2000. That's not many, but it gives consolation to Libertarians, whose party has never won a state or legislative office in Wisconsin.
Only two third-party candidates, both independents, have held seats in the Assembly since 1947. None have been elected to the Senate or a statewide office in that time.
Burke believes this year is different. His party has candidates running for lieutenant governor, attorney general, secretary of state, treasurer, Congress and a swath of stte Assembly and Senate seats. The Internet and social media also have made the party's message more available to voters.
Libertarians typically push Republicans to the right, while Green Party candidates and independents pull Democrats left, Lee said.
Burke, who worked in the health care industry, criticized Walker's relationship with the Wisconsin Economic Development Corp., which the governor created to replace the former Commerce Department. State government has gotten too cozy with business, Burke said, but he also faulted Democrats for relying on big government to create jobs and for pandering to voters. Neither part has helped the nation's poor, he added.
"We believe you know how to make yourself happy best," said Bob Burke, a former Republican. "And if you can do that without hurting anyone else's life, liberty and pursuit of happiness, we're going to help you do that."
The directors of the Wisconsin Democratic and Republican parties - Mike Tate and Joe Fadness - didn't return repeated requests for comment on how they plan to address the threat posed by third-party candidates.