I think it’s a separate question whether Joe Biden is wrong about the Republican Party or he is just saying these things because it feeds into what people want to believe.

As Joseph R. Biden Jr. made his way across Iowa on his first trip as a 2020 presidential candidate, the former vice president repeatedly returned to one term — aberration — when he referred to the Trump presidency.

“Limit it to four years,” Mr. Biden pleaded with a ballroom crowd of 600 in the eastern Iowa city of Dubuque. “History will treat this administration’s time as an aberration.”

“This is not the Republican Party,” he added, citing his relationships with “my Republican friends in the House and Senate.”

I write about the importance of leadership a lot, and I think it’s true that there are a lot of things about Trump that are unique to Trump. He is influencing the GOP is negative ways, and a different leader could take them in different directions. Even if Trump tapped into something latent or pathologies that were deemphasized, he has succeeded in amplifying these things and bringing them to the forefront where they can do more damage. So, I don’t think it’s entirely wrong for Biden to say that Trump is having an aberrant and possibly temporary affect on the Republican Party.

I would generally not place my focus on this somewhat optimistic take however because I believe Trump’s influence will not quickly fade. He has reshaped the electorate and the makeup of the Republican base, making it harder and harder for moderate Republicans to win in contested primaries or suburban areas of the country. This is why defeating Trump won’t return us to the status quo ante. To the extent Biden is suggesting otherwise, I think he’s wrong.

There is no disagreement among Democrats about the urgency of defeating Mr. Trump. But Mr. Biden’s singular focus on the president as the source of the nation’s ills, while extending an olive branch to Republicans, has exposed a significant fault line in the Democratic primary.

Democrats, like Senators Bernie Sanders and Elizabeth Warren, see the president as a symptom of something deeper, both in a Republican Party overtaken by Trumpism and a nation cleaved by partisanship. Simply ousting Mr. Trump, they tell voters, is not enough.

This doesn’t quite capture the divisions on the left. Democrats naturally have a passing interest in how the Republicans behave and would like them to rejoin the community of the sane and somewhat moral. But progressives and liberals have their own agenda they’d like to pursue and advance. So, if defeating Trump might get the GOP to behave in a less appalling manner, that would be nice, but doing something to address climate change or gun violence or police brutality is more important and certainly more within the left’s control.

The real splits on the left are more economic in nature or just boil down to differences of opinion about how the deep the rot in our society has become and how far we need to go to fix it. Warren and Sanders are in the camp that sees little comfort in returning to the past. Biden offers more of a band-aid approach. If we can fix what’s gone wrong, we should be able to gets things back in order.

It’s a debate that goes beyond the policy differences separating a moderate like Mr. Biden from an insurgent like Mr. Sanders, elevating questions about whether the old rules of inside-the-Beltway governance still apply. And it has thrown into stark relief one of the fundamental questions facing the Democratic electorate: Do Democrats want a bipartisan deal-maker promising a return to normalcy, or a partisan warrior offering more transformative change?

Many people on the left simply don’t want a return to normalcy, and Biden is not going to be their first choice. But I think the larger electorate is actually approaching desperation in their desire for the insanity to stop. They’re going to like what Biden is selling even if it is based on delusions.

I don’t know what Biden actually believes, but I’m confident that what he’s saying is wrong in important respects. The GOP is much farther gone than he’s willing to acknowledge. Yet, I think his approach is probably good politics even if it makes liberals insane.