Editor’s Note: For an alternative viewpoint, please see: Counterpoint: Dems and GOP — Two Wings of the Same Party

Freshman Sen. Ben Sasse, R-Neb., recently made headlines with an impassioned plea for a “healthy” alternative to Hillary Clinton and Donald Trump. He denounced not only the two presumptive candidates, who he said are “dishonest and have little chance of leading American forward,” but also their parties, which he said “bicker like children about tiny things, and yet … can’t even identify the biggest issues we face.”

Says Sasse: “These two national political parties are enough of a mess that I believe they will come apart. It might not happen fully in 2016 … but when people’s needs aren’t being met, they ultimately find other solutions.”

At some level, that last part has to be right. The lines of political contestation between the two dominant political parties have changed before, and they seem to be changing again. And so it is natural to ask whether a major third party can force its way into contention, disrupting our political duopoly.

There are plenty of reasons for skepticism. Ballot access laws vary greatly across the country, but many states require hundreds of thousands of signatures. That makes it very expensive for new parties to break in. By long habit, most Americans think of voting for a third party as a purely expressive act with no hope of immediate impact. And America’s first-past-the-post elections strongly push toward a two-party equilibrium.

All these factors mean that recurrent dreams about the emergence of a centrist or non-political party face especially long odds. The moment someone tries to call such a party into existence, it will be attacked on both flanks by the established parties. And it is hard to generate the needed grassroots excitement around a message of resolute centrism or a suspension of normal political hostilities. Michael Bloomberg’s decision not to run confirms this logic.

To make a lasting difference, a third party must organize around some issue that divides the public and yet is mostly neglected by the two major parties. In the late 1840s and 1850s, this issue was slavery: in spite of deep anxieties about the “peculiar institution” in both the north and south, Democrats and Whigs worked to suppress the issue in national politics. That allowed the Free Soil and Republican parties, which featured opposition to slavery’s expansion as their central issue, to emerge as disruptive forces. Abraham Lincoln took the White House for Republicans less just six and a half years after the party was founded, and the rest is history.

Third parties today can hope to catalyze some kind of similar transformation. Even if the labels “Democrat” and “Republican” stay with us, the ideas and commitments of each party may be profoundly altered such that more citizens are satisfied by one of the choices on offer. The question then becomes: when people like Senator Sasse reject both sides of the choice between Hillary’s Democrats and Trump’s Republicans, what sort of concerns are going unaddressed?

For #NeverTrump die-hards like Sasse, the answer is a respect for America’s constitutional heritage, conservative values and tradition of limited government. These ideas, central to movement conservatism’s self-image, seem suddenly divergent from what the Republican Party is becoming. But the desire to recruit a prominent candidate to champion these ideas in the presidential election seems not to have captured the imagination of a large slice of the public, nor even of political elites, and so the effort to create a kind of True Republican insurgency looks set to fizzle.

Arguably the Libertarian Party might be positioned to benefit. It will be the only third party on all 50 state ballots. Its standard-bearer in 2012, Gary Johnson, the former governor of New Mexico, received nearly 1.3 million votes, or 1 percent of all ballots cast. This year, Johnson looks set to run again, this time with former Massachusetts Gov. William Weld as his running mate. Armed with this respectable ticket and the message that they will support economic and social freedoms no longer protected by Democrats or Republicans, this year may be Libertarians’ best chance for a breakthrough. A long institutional history of putting doctrinal purity ahead of political success may make it difficult for them to seize the opportunity, though.

Whatever shape it might ultimately take, an issue-driven third party contesting the shared assumptions of Democrats and Trumpian Republicans could play a constructive role in reorienting American political conflict. Like Britain’s Liberal Democrats, who defied the tendency toward a two-party system and forced their way into a coalition government with David Cameron’s Conservatives from 2010 to 2015, such a party could do a great deal to help America through one of our nation’s most confusing political moments.