Just What Kind of a Third-Party Candidate Is R.F.K. Jr.?

With six months to go until the election, it’s still too early to judge whether Robert F. Kennedy Jr., the Democrat-turned-independent candidate for president, will prove to be more than a mere spoiler.

He starts out with roughly 10 percent of the vote and one of the most famous names in American politics. It’s enough to at least contemplate whether he’ll be the kind of third-party candidate who makes a lasting mark.

Even without having won the presidency, third-party candidates have often played an important and even healthy role in American politics.

They can elevate new issues, represent marginal constituencies and sometimes even win plenty of votes: Six third-party candidates have either won states or reached double digits in the national vote since the rise of the two-party system. They can be a lot more than mere spoilers.

The polling shows many of the conditions for a successful third-party candidacy could be in place. Voters dislike both candidates. They’ve been dissatisfied with the state of the country for 20 years, but for the most part the campaign season hasn’t been focused on solutions to customary longstanding problems. It’s enough to wonder whether this might be the first time since 1992 that a third-party-candidate gains a meaningful foothold.

To understand the Kennedy campaign, it’s worth looking at how similar kinds of third-party bids have managed to gain support in the past, or fallen short of making a splash. For simplicity, I’ve broken down third-party candidacies into three groups that Mr. Kennedy plausibly reflects. The groups are not mutually exclusive — historically, many candidates exhibit the traits of multiple categories, and so does Mr. Kennedy. The taxonomy also mostly applies to transient third-party bids like Mr. Kennedy’s, not the campaigns of established minor parties (Green, Libertarian, Constitution and so on). The categories might help make sense of what it would take for Mr. Kennedy to be more than a mere spoiler in this election.

The movement candidates

Every so often, a new set of problems and issues rises to the forefront of American politics — and the major parties simply aren’t positioned to address them. In these cases, the new issues don’t neatly map onto the existing political alignment. They could even be so orthogonal to the usual political divide that it would be deeply painful and divisive for a party to try to take them on. An issue might even risk breaking up a major party, as the future of slavery did in the 1850s (the Whigs no longer exist).

When important issues go unaddressed, a third-party candidate often comes along to bring them to the fore. Historically, these third parties tend to be fleeting. Their issues fade, whether because things get better or because the major parties ultimately do enough to satisfy their demands. (The famous exception being the run-up to the Civil War.) But until they fade, these movements look and feel like a major third party. They’re usually for something, something big that draws significant support, whether it’s free silver or reducing the deficit.

It takes a fairly special set of circumstances for a third-party movement like this to emerge — usually when neither party can meet the movement’s demands. This was routinely the case from the end of Reconstruction until the Great Depression, as the two-party system was still defined by the legacy of the Civil War and slavery, not the immense challenges unleashed by industrialization. With the exception of the Progressive Era, the two parties were usually led by relatively conservative wings, creating an opening for frequent progressive, populist and socialist candidacies that sought to break corporate power and protect workers and farmers. These campaigns often won considerable support until the rise of the New Deal brand of modern liberalism, which combined with postwar affluence to mostly satisfy the issues and constituencies of the age.

These types of progressive-outsider candidates have become less frequent since the rise of a liberal Democratic Party. Instead, recent third-party movements have emerged from the populist right, which was alienated by the newly liberal Democratic Party but never had a comfortable home within the classically liberal, elite Republican establishment. As a result, there have been openings for nationalist, conservative populists, from George Wallace to Ross Perot, who appealed to Democrats and Republicans alike. There are echoes of these campaigns in Donald J. Trump, who may ultimately represent the final integration of their demands into a remade, populist Republican Party.

Mr. Kennedy doesn’t fit that particular mold, but can he lead a different third-party movement? On paper, there are plausible opportunities. Neither party is credible on spending and the debt, which may contribute to inflation and high interest rates. Neither party focuses on the various crises of isolation, obesity, homelessness, addiction and mental illness, which don’t map onto the usual left-right divide and which might be just as important as any material challenge in American life.

With the campaign just getting underway, it seems premature to declare that Mr. Kennedy can’t become a movement candidate. He does talk about some of these issues already, and this is not an exhaustive list of the plausible opportunities for a vigorous third-party bid — consider other issues like the cost of child care, education and housing.

But Mr. Kennedy is not this candidate today. His arguments aren’t putting any visible issue-based pressure on the major parties. Few ask Democrats or Republicans whether they support anything Mr. Kennedy argues for, as his policy agenda and political message are not especially focused. His anti-corporatism is mostly expressed in generalities. And despite the potential for a broader message, he’s best known for idiosyncratic views on vaccines — he’s been a longtime critic and skeptic — and environmental protection, which to this point seem to elicit a cringe from the establishment, not fear.

The factional dissenters

There’s another group of candidates whose demands do mostly align with the pre-existing two party system, but who break away regardless: the factional dissenters.

These candidates draw support from a dissatisfied faction of a major party. Often, it’s because the major party has done something the group dislikes. Maybe the party has drifted too far to the center. Maybe it’s gone too far to an extreme. Either way, the discontents of one party rebel and tend to draw most of their support from that party. They have potential spoiler written all over them.

These candidates have become familiar in the era of ideological, left-right partisan politics. There’s Henry Wallace, who ran as a progressive in opposition to Harry Truman’s hostility to the Soviet Union at the start of the Cold War. There’s Strom Thurmond and George Wallace, the white supremacist Southerners who bolted from the Democrats over their embrace of civil rights. Then there was John Anderson, a liberal Republican who thought his party had gone too far to the right in 1980. Even more recently, Ralph Nader in 2000 could count (though his Green Party is an established minor party), as could Evan McMullin, the independent candidate who ran for president in 2016 as a more-or-less traditional Reagan conservative and won 21.5 percent of the vote in Utah.

Factional candidates don’t usually do too well, and they’ve been faring worse over time. The parties have gradually become more ideologically consistent, leaving fewer opportunities for dissenters. And as politics has become more polarized, the stakes of “wasting” one’s vote and allowing the other party to win have grown as well.

Is Mr. Kennedy a factional dissenter? He looks like one at first. But even though he was a Democrat at the start of the campaign, he doesn’t represent a dissenting faction of Democrats who are deeply upset with President Biden or the mainstream of the party. He’s not critiquing Mr. Biden on Gaza, for instance; in fact, he’s taken a pro-Israel stance. His main criticism of Democrats isn’t that they’re too centrist, either. His most distinguishing views, on vaccines, aren’t really tethered to a critique of Mr. Biden and the Democrats. This is not another Ralph Nader.

The protest candidates

Almost by definition, nearly every minor-party candidate benefits from protest voters — people who cast a ballot for a third-party candidate mostly because they dislike the major- party candidates and politics as usual.

But more recently, there have been relatively prominent third-party candidates who seem to garner support almost exclusively from protest voters, not because voters want to send a message on the issues.

This is a relatively new phenomenon. Believe it or not, the 2016 presidential election was the first in the polling era in which both candidates were viewed unfavorably by a majority of voters. Consequently, the Libertarian Party’s candidate in 2016, Gary Johnson, might be the first noteworthy candidate who was mostly the recipient of an empty protest vote. He won 3.3 percent of the vote, and there is little evidence that most of those voters were trying to show their support for libertarians or his message. In contrast, the voters who disliked both candidates but chose Jill Stein or Evan McMullin were more clearly embracing an ideological critique of their usual party’s candidate.

Of all the categories so far, this is the one that Mr. Kennedy fits best. At the start of the campaign, he’s a brand-name candidate who isn’t Mr. Biden and Mr. Trump. If this is all Mr. Kennedy proves to be, his support will probably steadily decline as the campaign continues. (Mr. Johnson also held nearly 10 percent support in the summer of 2016.)

One thing Mr. Kennedy has going for him is one of the most famous names in politics. His broad anti-corporate, anti-bureaucracy, anti-system appeal may also resonate naturally among the kinds of voters who tend to dislike both parties and candidates.

Historically, there’s not much reason to expect a candidate like this to be anything more than a possible spoiler. But perhaps the growing number of voters dissatisfied with American politics creates a better chance for such a candidate to succeed today. This kind of minor-party candidate could be new but might be with us for a long time to come. Perhaps we haven’t seen the strongest of them yet.