Many Americans value environmental protection and want to see more of it. But Jill Stein, the Green Party presidential candidate, is drawing only 1 percent to 3 percent in recent polls, even in an election where many voters dislike the major candidates and are looking for alternatives.

Stein certainly has worked to differentiate herself from the two major party candidates. In July, she asserted that electing Democratic nominee Hillary Clinton − probably the choice of most pro-environment voters − would “fan the flames of . . . right-wing extremism” and be as bad as electing Donald Trump.

While Stein makes anti-establishment statements like this, her German counterparts have been advancing a green agenda in local, regional and national government for the past 30 years. Most recently, Winfried Kretschmann was re-elected this year as head of government in Baden-Württemberg, one of Europe’s technologically and industrially most advanced regions.

I grew up in Germany and have taught about Germany and Europe in the United States for the past 15 years, so I have seen Green Party politicians at work in both countries. In my view, there are two reasons why the U.S. Green Party remains so marginal. Structurally, the American electoral system is heavily weighted against small political parties. But U.S. Greens also harm themselves by taking extreme positions and failing to understand that governing requires compromise.

Both European and North American Green Parties evolved from activist movements in the 1960s that focused on causes including environmentalism, disarmament, nuclear power, nonviolence, reproductive rights and gender equality. West German Greens formed a national political party in 1980 and gained support in local, state and federal competitions.

The German Green Party’s rise owed much to the country’s electoral system. As in many continental European democracies, political parties win seats in German elections based on the percentage of voters that support them. For example, a party winning a third of the popular vote will hold roughly a third of the seats in the parliament after the election. Proportional representation makes it possible for small parties to gain a toehold and build a presence in government over time.

In contrast, U.S. elections award seats on a winner-takes-all basis. The candidate with the most votes wins, while votes cast for candidates representing other parties are ignored.

In Germany, Greens had to develop a capacity for compromise. To gain power, they had to form coalitions with center-left Social Democrats. Working through alliances, former activists initiated reform of an antiquated immigration and citizenship law and worked toward recognition of same-sex unions. They implemented an environmentally driven tax code and brokered a deal with the nuclear energy industry to cancel projects for new plants and phase out nuclear power by 2022.

There is no easy way for the U.S. Green Party to emulate its German counterparts. Because the American political system makes it difficult for third parties to participate, Green Party candidates do not have opportunities to learn the trade of politics. They have remained activists who are true to their base instead of developing policy positions that would appeal to a broader audience. By doing so, they weaken their chances of winning major races even in liberal strongholds.

This suggests that running on a third-party ticket in the United States is still not a winning route to shaping a message aimed at a broad electorate. Instead, climate change, dwindling energy resources and growing human and economic costs from natural disasters will do more to promote ecological consciousness and political change in mainstream America than the radical rhetoric of the U.S. Green Party.

Per Urlaub is associate professor of German studies at the University of Texas. She wrote this for the Washington Post.