The usual rap against Libertarians is that they are too dogmatic, too unwilling to compromise on their core commitments to individual liberty and limited government, even if that means political marginalization. So it is odd that Gary Johnson, the Libertarian Party's presidential nominee, and his running mate, Bill Weld — both highly successful former GOP governors from blue states — are now facing criticism from some conservative quarters for not being dogmatic enough.

Fair or unfair, Johnson and Weld need to take this criticism seriously. Because the 2016 election — which pits a stupid candidate from the Evil Party against an evil candidate from the Stupid Party — presents a potential third-party challenger with a real opportunity. But to capitalize on it, Johnson will have to present himself as a credible alternative to Hillary Clinton and Donald Trump whom voters can take seriously. He needs to do more.

The Week's Michael Brendan Dougherty lamented that the Libertarian Party's 2016 nominees are "super qualified but entirely unappealing." Likewise, Washington Examiner's Tim Carney commented that conservatives looking for a plausible third-party alternative shouldn't turn to the libertarian ticket because it has decided to run "against conservatives more than for liberty." Indeed, noted Carney, Johnson and Weld seem to be signaling, "We don't need those backward Christian Right bozos as much as we need you MSNBCers." The Federalist's David Harsanyi echoed similar sentiments.

Apart from the fact that Johnson and Weld are both pro-choice — Johnson moderately and Weld strongly — what triggered this widespread angst on the right was Johnson's comment that he would be fine with legally requiring Catholic bakers to service gay weddings. Freedom of conscience is a bedrock Libertarian tenet and a key reason why many serious religious believers gravitate toward Libertarianism — notwithstanding the common perception of it as a secular philosophy that believes in laissez faire economics and morality. Hence, Johnson's concession on religious liberty is without a doubt troubling for many Libertarians as well as conservatives.

Purity is not possible in politics. But Johnson has to be principled if he wants to hang onto his natural constituency while expanding his appeal to other voters. His gay wedding cake capitulation will alienate religious Libertarians without gaining any MSNBCers, the vast majority of whom are already in the tank for Hillary.

No doubt, what's really driving Johnson is a desire to avoid tripping up like Sen. Rand Paul, who drew withering criticism several years ago when he expressed qualms to Rachel Maddow about the 1964 Civil Rights Act's ban on private racial discrimination. Paul staked out this position not because he is racist, but because, like a small subset of Libertarians, he believes using government coercion for noble ends inevitably backfires. If whites can't discriminate against blacks, then that also means that blacks can't discriminate against whites, which means black restaurants couldn't turn away KKK diners. And if the ban were extended to religion, Jews would have to serve Nazis.

Most Libertarians accept that using government force to end private discrimination under the Civil Rights Act was necessary to undo two centuries of government-enforced private discrimination in the form of slavery and Jim Crow. There is no equivalent parallel in history and therefore there is no strong reason to extend that ban to other groups. In other words, a Libertarian could have accepted the Civil Rights Act and also drawn some principled limits to it, rather than signing off on a wholesale abridgement of religious liberties, as Johnson has.

Last time Johnson ran, I called him a "pragmatic champion of liberty" because he offered relatable arguments for his positions. He will have to double down on that approach now. He describes himself as "fiscally conservative and socially liberal," which is fine as far as it goes, but he can't stop there. Other politicians can get away with little beyond bromides and vague promises. He can't — not if he wants to get attention, at any rate. He needs to get specific.

He says he'll cut federal spending by 20 percent — including on entitlements, a noble stance given the absolute cowardice of the political class in dealing with the certain fiscal catastrophe that awaits this country if nothing is done. But that's not enough. He can't sell spending cuts as ends unto themselves just because Libertarians believe in limiting the size and scope of government. He has to explain why, and offer bold — and detailed — reform plans for Social Security privatization or replacing entitlement programs with a universal basic income. James Spiller's recent National Review hit piece questioning Johnson's stellar fiscal record as governor of New Mexico was a travesty. But he was right in pointing out that Johnson's pledge that as president he'd veto any budget with a deficit just doesn't cut it. It won't persuade voters that he's serious and it won't affect the terms of the debate, which is his sole purpose for running given that his chance of actually winning the White House is only slightly better than David French's was.

Above all, however, to truly gain traction, Johnson must take his cues from voters' actual concerns, and not simply try to sell them on Libertarian hobbyhorses. He needs to create a bigger agenda based on what's on voters' minds. That means focusing on Libertarian solutions for core economic, social, and national security issues — not just bloodless opinions on them when queried, which is what he's been doing. He has to offer Libertarianism not as an ideology but as a solution.

This is undoubtedly a tall order. But "we stink less than the other two" isn't the kind of message that will excite the refugees of the two main parties to make the schlep to the polls and vote Libertarian on election day. Just as many women would attest that they have to be twice as good as the next male to get ahead in many workplaces, Libertarians have to be twice as good as major-party candidates to win the hearts of mainstream voters. Johnson, who obtained 1 percent of the vote in 2012, is already the top choice of 10 percent of voters — even 12 percent in a Thursday Fox poll — which is remarkable for a Libertarian candidate. But to truly make Libertarian ideas matter, he'll have to up his game.