“This election,” a spokesman for Sen. Ben Sasse (R-Neb.) said Thursday, “remains a dumpster fire.” Well, yes, the two major-party candidates for president are historically unpopular. But if this election is unusually bad, it is not because both parties chose bad candidates. There is no equivalence between Donald Trump and Hillary Clinton — as even responsible Republicans should be able to recognize.

Ms. Clinton is a knowledgeable politician who has been vetted many times over. She understands and respects the U.S. Constitution. She knows policy. She can cite accomplishments in the public interest, such as pressing through an important children’s health insurance program during her husband’s administration. As a senator, she was respected by colleagues on both sides of the aisle. She completed four years as secretary of state to generally positive reviews. She began her presidential campaign by rolling out a series of serious policy papers.

[Former RNC chairman: Americans can choose better than Trump]

None of this means you have to like Ms. Clinton or believe she would be a good president. You may disagree with her views; we have done so often enough and will do so again when we think she is wrong. You may believe she was foolish to push for the Libya intervention, arrogant to keep her emails out of the official State Department server, greedy to take large speaking fees as a private citizen. But measured against other major-party candidates of recent times, Ms. Clinton is well within established bounds of competence, knowledge, commitment and integrity. She is not a dumpster candidate.

Mr. Trump, by contrast, has waged a campaign based on bigotry, ignorance and resentment. He has no experience as a public servant, and his private record of bankruptcies and exploitation should be disqualifying. He regularly circulates falsehoods. He has no dis­cern­ible interest in or knowledge of policy. Just in recent days, Mr. Trump tweeted out an anti-Semitic image circulating on neo-Nazi websites and attacked the media for reporting as much. He called one sitting senator a loser and threatened another while proving that he lacks even a passing familiarity with the Constitution. He praised one of the most vile dictators of the 20th century.

A whole host of influential Republicans have decided not to attend July's Republican National Convention in Cleveland. (Peter Stevenson/The Washington Post)

[Henry Paulson: When it comes to Trump, Republicans must choose party over country]

Those Republicans with enough self-respect to be mortified by the man their party is about to nominate continually hold out hope for some magical transformation. Yet even if Mr. Trump flipped his agenda — not a problem for a man with almost no fixed beliefs — he would still be the candidate who mocked a disabled reporter, proposed banning Muslims from entering the United States, attacked a judge based on his ethnicity, celebrated violence at his rallies, demeaned women and promised to round up and deport 11 million undocumented immigrants . He would still be the candidate who vaulted to political prominence with race-based attacks on the incumbent president and launched his campaign by calling Mexicans rapists.

Mr. Sasse has proved to be a rare Republican official with the moral courage to speak as honestly about Mr. Trump after he clinched the nomination as he did before. It’s not surprising that the senator would want to dismiss the whole campaign as a mess, and we don’t doubt that he genuinely fears the direction in which Ms. Clinton would lead the nation.

But to equate the two candidates as indistinguishably unqualified products of a rigged or failed system only feeds public cynicism while blurring distinctions that should not be blurred. Ms. Clinton is a politician, long in the arena, whom you may or may not support. Mr. Trump is a danger to the republic.