American politics has become a test of allegiance. Candidates are expected to defend their party’s nominee, voters are urged to treat every election as an existential battle and dissent is quickly branded betrayal.

That is not strength. It is a warning that party loyalty is crowding out independent judgment.

The country has always had sharp political disagreements. Parties have offered voters different visions and organized people around shared goals. But parties are instruments of democracy, not its owners. They are meant to serve the public, not demand unquestioning loyalty from it.

Today, too many political leaders seem more concerned with defeating the other party than addressing the problems voters face. They turn opponents into enemies, portray compromise as weakness and use outrage to keep supporters engaged. The result is a politics in which winning the next election can matter more than governing well once it is over.

That pressure reaches beyond Washington. When a politician breaks with the party line, the response can be swift and personal: condemnation, exclusion and demands to fall back in line.

In the short term, that may satisfy the party faithful. In the long term, it narrows debate and teaches elected officials protecting their standing matters more than speaking honestly.

Recent political disputes have shown how quickly disagreement over a candidate’s words or conduct can become a loyalty test. Voters may reasonably disagree about where to draw the line. But they should not be told that raising questions about a nominee makes them disloyal. Nor should any candidate be excused from scrutiny simply because that candidate carries the preferred party label.

That dynamic is on display in Michigan this week, where Democratic Rep. Haley Stevens endorsed Republican Mike Rogers in his Senate race against Democratic nominee Abdul El-Sayed. Stevens faced swift backlash from within her own party and accusations that she was a traitor.

The same standard must apply to both parties. Democrats and Republicans each have voters who feel ignored by their leadership and both parties have incentives to treat internal criticism as a threat. Neither can claim to defend democratic principles while punishing every member who exercises independent judgment.

This is not an argument that party affiliation means nothing. Parties shape policy, choose candidates and give voters a practical way to express their priorities. But a party label cannot establish a person’s honesty, character or capacity to govern. Those judgments require attention to a candidate’s record, words and choices.

Voters also have a responsibility. If they excuse conduct from their own side they would condemn in the other, they encourage the very cynicism they say they deplore. A party that believes its supporters will never leave has little reason to listen to them.

Party loyalty can be a source of community and purpose. It becomes dangerous when it asks citizens to surrender conscience. A healthy democracy needs parties strong enough to compete and open enough to tolerate disagreement. Most of all, it needs voters willing to put the country, the truth and their principles ahead of partisan comfort.

Baltimore Sun Editorial Board