An hour into the first night of the Democratic National Convention, former Ohio Governor John Kasich gave the expected argument. “I’m a lifelong Republican,” he said. “But these are not normal times.” He praised Joe Biden’s “experience, and his wisdom, and his decency.”

Then Mr. Kasich said this: “I’m sure there are Republicans and independents who couldn’t imagine crossing over to support a Democrat. They fear Joe may turn sharp left and leave them behind. I don’t believe that. Because I know the measure of the man: reasonable, faithful, respectful. And you know, no one pushes Joe around.”

This was contradicted 25 minutes later, when Bernie Sanders arrived to declare ideological victory. “Let me offer you just a few examples of how Joe will move us forward,” Mr. Sanders said. “Joe supports raising the minimum wage to $15 an hour.” He’ll “fund universal pre-K for 3- and 4-year-olds.” He’ll “fight the threat of climate change by transitioning us to 100% clean electricity over the next 15 years.” He’ll “lower the eligibility age of Medicare from 65 down to 60.”

More than a few Republicans think Donald Trump’s character and temperament are so flawed that he can’t be trusted again with the Presidency. Fair enough: Character matters. But please don’t pretend that a Biden victory, with a Democratic House and likely Senate, will produce a centrist revelation of bipartisan comity. Bernie Sanders probably has more insight on that one than Mr. Kasich.