The landscape of American history is littered with the corpses of failed political parties. The Whigs, the Populists and the Know-Nothings are only some that have fallen by the wayside. One political party in the U.S. has now turned into a dark corner of history and may founder, too, if it doesn’t right itself.

The Republican Party, once the party of Lincoln, racial equality and women’s rights, backs a man who scapegoats people simply for being different: gays seeking equality, blacks who stand up against police brutality, immigrants, feminists, refugees ... . President Trump has a long list. Trump loves a fight, so he always seeks opposition. Trump’s party, long known for pragmatism and compromise, now joins him in finding new enemies, including leaders of allied nations. The GOP backs a man whose favorite political tactic is dividing the country by trolling his opposition.

The Republican Party has followed President Trump into a tariff war and a foreign policy that alienates longtime allies while cozying up to isolated dictatorships like Russia and North Korea. These policies are a sharp reversal from long-held conservative principles of advancing American economic interests and democratic values abroad. The GOP once stood against fascists, racists and communists. Now it joins its leader in embracing them. Republicans flirt with disaster when their president flirts with communists, white supremacists and strongmen.

It’s easy to overlook the changes in the GOP. Trump thrives on press coverage and constantly feeds the news cycle with fresh distractions. But what is happening to the GOP is the real story. A party that once passed major bipartisan legislation can’t agree on an immigration bill, even when it controls all three branches of the federal government. Instead of cutting taxes for the middle class, the GOP cuts taxes for the rich and favors tariffs that increase prices for the rest of us and lead to layoffs. Instead of uniting the country and promoting opportunity, the GOP backs a man who scapegoats poor refugees seeking asylum and constantly seeks to divide us from one another, all for immediate political gain.

Current Republican policies are shortsighted and destructive. American values of inclusion, equality, justice and freedom have spread across the globe along with American goods, films, music, culture and art. America grows more complex, more racially diverse and more accepting of differences, while the GOP stonewalls and backs simple-minded nationalism masked as self-interest. America can flourish as a pluralistic country that leads the world by promoting humanitarian missions and protecting an interdependent system of global free trade. But the GOP has turned its back on that vision. It has turned to a vision of a country dominated by white supremacy, Christian identity and nativism. This is not only a waste of America’s promise, it’s a dead end.

Republicans must face the inevitable changes of our time or their party will face its inevitable self-destruction. No great party can govern by dividing us from one another. No economy can grow when it’s cut off from trade and the free exchange of ideas. And no superpower can lead the world by turning away from its allies and acting only in its own short-term self-interests. Yet as Trump divides, quarrels with our allies and seeks only short-term advantage, his party bows to him. His base is in thrall to him, and the Republican leadership, instead of leading, is led by his radical nativist supporters.

As long as the Republican Party follows Trump and his base, it leads America into disappointment, division and despair. It is time to vote against the GOP to prevent making our future a dark corner, too.

Matthew R. Brown of Harwich teaches history at Monomoy Regional High School.