Libertarians could hurt somebody's campaign, but whose?

Gary Johnson and Bill Weld may be the Ralph Naders of 2016, though it's not clear whether the casualty would be Donald Trump or Hillary Clinton.

Johnson and Weld, former Republican governors, were tapped last weekend as the Libertarian candidates for president and vice president. This party has never received even 1 percent of the vote in a presidential election.

But never have the two presumptive major party nominees been so unpopular. Thus the Johnson-Weld ticket hopes to get the highest third-party vote since Ross Perot captured 19 percent running as an independent in 1992.

They wouldn't necessarily need big numbers to make a big impact. Nader, running as the Green Party candidate, received less than 3 percent of the total vote in 2000. But he probably cost Democrat Al Gore the election by taking ballots Gore needed to capture decisive electoral votes in the excruciatingly tight contest in Florida.

Polls show receptivity to a third-party candidacy this year, but there is no reliable data measuring the appeal of the Johnson-Weld ticket. Ann Selzer, a top pollster based in Des Moines, Iowa, who conducts surveys for Bloomberg Politics, wonders if initially it would come from disgruntled backers of Bernie Sanders's challenge to Clinton.

"Sanders supporters averse to supporting Clinton might give the libertarians a look," Selzer said. "For now."

Most of the fire from the Libertarian nominees so far has been directed at Trump, with Weld even drawing parallels to what happened in Nazi Germany in the 1930s. The viability of Johnson and Weld depends on several evolving factors. One is whether anti-Trump Republicans find another independent candidate. Another is whether the Libertarians could poll strongly enough to participate in this fall's presidential debates, assuming they transpire; they'd need a 15-percent showing, a tall order.

Libertarians share with Republicans a devotion to free markets and opposition to tax increases and government spending, so their ticket might be a convenient parking spot for moderate and economically conservative Republican voters who can't stomach the ideologically malleable Trump. There are a number of libertarians in the Republican coalition, including two one-time presidential hopefuls, former Texas Rep. Ron Paul and his son, Kentucky Sen. Rand Paul.

But Johnson, who was governor of New Mexico from 1994 to 2003, and Weld, the Massachusetts chief executive from 1991 to 1997, will have little appeal to social conservatives because Libertarian positions on abortion and gay marriage align them with liberal Democrats. Nor are they likely to win favor from foreign policy hawks hostile to their non-interventionist views.

They might have more appeal to some Democrats and independents leery of Clinton. Clinton's negatives are unusually high among younger voters, many of whom are sympathetic to Libertarian opposition to criminal penalties for drug use. There probably wouldn't be much support for Libertarians among Latinos and African-Americans or with labor-oriented voters.

And there are fringe positions that may alienate some potential voters. Libertarians are skeptical of social security and their opposition to most laws against recreational use of drugs extends even to hard drugs like heroin. Johnson doesn't support outlawing government-issued driver's licenses, but many libertarians do. And he ducked a question put to him on Saturday during a debate at his party's Orlando, Florida, convention on whether the U.S. was justified fighting World War I and World War II.

Still as a protest vehicle against two flawed candidates and the possibility of financial backing from anti-government fat cats, Johnson-Weld can't be dismissed. And in a year where success has come to a Vermont socialist and a billionaire business and entertainment mogul who revels in insults and invective, all bets are off.