A supporter of 2016 Republican presidential candidate Donald Trump has...

A supporter of 2016 Republican presidential candidate Donald Trump has her photo taken outside a Trump campaign rally at the Radford University Dedmon Arena in Radford, Virginia, on Monday, Feb. 29, 2016. Credit: Bloomberg/ Andrew Harrer

If you need proof that the two established parties don’t represent enough Americans, come to Colorado, which holds its nomination caucuses on Super-Tuesday. In this swing state, neither Republicans nor Democrats have a plurality of registered voters, but the parties have rigged the rules so that voters have as little say as possible in the selection of presidential candidates.

This year, Colorado’s primary process provides an example of a broader problem with the country’s political system: Far too many Americans aren’t represented.

Everyone I talked to in Denver has mentioned what is variously defined as Colorado’s “frontier mentality,” “Wild West feel” or “libertarian streak.” The state is the birthplace of the Libertarian Party, which has 24,000 active registered voters here, but the independent voters are mainly registered as unaffiliated. There are 1.3 million such independents compared with 1.1 million each for the Democrats and Republicans.

Support for maximum liberty straddles political lines. This translates into voter backing for a set of political causes championed by both traditional parties: pot legalization and the energy industry’s freedom to frack; abortion rights and a small government. According to Christy Powell, who works for Project New America, a company in Denver that does polling and strategy consulting for progressive organizations:

Small government libertarianism works for a lot of Western voters, so even in issues such as reproductive choice ’government needs to get out of my business’ is a more accessible framework. The Republican side has done a good job of pushing small government, and we can turn it on its head.

This peculiarity may bring voters together, but more often it divides them. According to Richard Wadhams, a former Colorado Republican Party chairman, independent Coloradans “don’t want to identify with the Democrats because they’re too liberal on spending or with the Republicans because they’re too conservative on social issues.”

The share of unaffiliated voters is growing. In 2006, they made up 34 percent of the rolls; now it’s almost 37 percent. It’s young people and relatively new arrivals in the state who swell the unaffiliated ranks. “People who move here for the quality of life and then stay can’t be taken for granted,” says Jill Hanauer, president of Project New America. “The customary labels are meaningless to the average voter, especially a millennial. Those over 50 are easier to classify.”

Indeed, the 26-40 age cohort is the biggest among the unaffiliated voters. Those 41-60 dominate the registered Republicans and Democrats.

Wadhams says that only 10 percent or 15 percent of the state’s voting age population are true swing voters: The rest more or less consistently support either the Democrats or the Republicans. Yet they prefer to keep their options open.

This elemental libertarianism seems to call for a strong grass-roots democracy, the kind I saw in Iowa and New Hampshire. Yet in Colorado in 2016, it wouldn’t stand a chance.

Both parties have chosen to keep the independents out of the primary process. On March 1, Colorado parties are holding closed caucuses, meaning that only voters who registered Democrat or Republican a month ahead will be allowed to attend. The Republicans have gone further: Their caucuses don’t even feature a candidate preference poll. The party’s state executive committee canceled it in August, ostensibly in response to national party rules that, according to one interpretation, bind a delegate to vote for a specific candidate if he declared his affiliation at the caucus stage.

Colorado’s system is the polar opposite of Iowa’s, where unaffiliated voters also constitute a plurality, but are allowed to register with the parties on voting day, and where both parties ask caucus-goers about their candidate preferences. In Iowa, with its 2.1 million registered voters, 357,983 people turned out for the caucuses. It was a genuinely democratic process. Turnout has been high in the other early states that held open voting in which anyone, including independents, could take part.

In Colorado, Wadhams proposed and held Republican preference polls in 2008, when 70,000 Republicans turned out, and in 2012, when 50,000 showed up. This year, he says, perhaps 15,000 die-hard activists will turn out in a state with 3.6 million registered voters (compared with the almost 187,000 Republicans who voted in Iowa, whose voting age population is 42 percent smaller).

Seth Masket, a political science professor at the University of Denver, suggests that Republicans may have canceled the vote intentionally to keep the turnout low. “It’s what they want,” Masket says. “They are concerned about Donald Trump and they want just the party regulars, the more mainstream voters.”

Colorado’s favorite Republican candidate will be determined through a four-tier process, in which only 1.3 percent of the registered Republicans will take part, and that just at the first stage. Obviously, this favors establishment candidates.

“Look, it’s a bummer that there’s no preference poll,” says Josh Penry, the former state senate minority leader who now serves as Marco Rubio’s Colorado campaign chairman. “We’re doing out best to get delegates for Marco through the arcane process that there is.”

I rather suspect that with five Republican candidates still in the race, Colorado’s undemocratic Republican primary system gives Rubio, now the party mainstream’s clear favorite, one of his few chances of winning a state.

The Democrats aren’t doing such an obvious job of keeping out voters who might back Bernie Sanders, but a closed caucus favors Hillary Clinton: The demographics of registered Democrats in Colorado match those of Clinton supporters. Many of the younger Coloradans who might have backed Sanders caught on to the rules too late, and they are still registered as independents and left out of the primary process.

Because the state parties haven’t thrown the doors open to independents and each other’s supporters, as they’d done in Iowa, candidates haven’t made too many campaign appearances here. As a result, the swing state’s public will get its say only during the national election in November. In 2016, that’s way too late. Some — or all — candidates who would have satisfied the independents’ demand for an outsider will be gone by then, kept out by the still-powerful party hierarchies.

“All the rules are gone” in this election, Wadhams says. That, however, doesn’t include the candidate selection rules. Of the states that have yet to vote, 29 have closed primaries that keep out swing voters and, more narrowly, backers of Trump and Sanders.

These rules, more than anything else, may determine who’s going to compete for the presidency. Trump and Sanders have both done well in states where the primaries were open (Trump also won in Nevada, where a Republican voter needed to register 10 days ahead of the caucus). If they manage victories in states with systems as unfair as Colorado’s, they will have overcome odds that were stacked against them.

If, on the other hand, they end up failing, that will only feed the trend toward the traditional parties’ irrelevance. About 40 percent of Americans — and the number is growing — identify as independents in polls. Voter registration will probably follow the trend, especially as Millennials begin to dominate the agenda.

The two parties are firmly entrenched, but by clinging to their power to select candidates, they may be slowly killing themselves. Independents whose political agendas cross party lines won’t always accept being limited to being able to only make the final choice, not the preliminary one.

Leonid Bershidsky, a Bloomberg View contributor, is a Berlin-based writer.

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