These polling problems, and the Democratic infighting that results from them, have Republicans feeling more confident about the November midterms. A more ethnically and racially diverse Republican Party has long been the Democrats’ worst nightmare and could help flip some Democratic-held swing seats. The party out of power usually gains congressional seats in off-year elections, and if Republicans can keep the focus on high inflation, rising crime rates and chaos at the border, this year should be no exception.

Looking past the midterms, however, the GOP still has a Donald Trump problem that Mr. Biden’s troubles can’t solve. Mr. Trump’s popularity among Republicans has declined, but not as much as you might think from media reports. According to the New York Times/Siena poll, 49% of Republicans said they would vote for Mr. Trump in 2024. That’s the lowest it’s been since he left office, but it’s still close to double the 25% of Republicans who favored Florida Gov. Ron DeSantis, Mr. Trump’s closest rival. Other choices included Ted Cruz, Mike Pence, Mike Pompeo and Nikki Haley, but none of them had more than a single-digit percentage of the vote.

Mr. Trump is well-situated at this early date to earn his party’s nomination for president if he chooses to run. In fact, he’s far more popular among Republicans than Joe Biden is among Democrats. In the same survey, only 26% of Democrats said they wanted Mr. Biden to run again in 2024, while 64% said someone else should be the party’s nominee. The problem for Republicans is that, however unpopular Mr. Biden is right now, polling shows that he still beats Mr. Trump in a theoretical rematch if the election were held today. Democrats may be down on their president, but they will almost certainly hold their nose and rally behind him if Mr. Trump is the Republican nominee—as they did in 2020, when pragmatism mattered more than purity. Far from denying Mr. Biden a second term, a Trump candidacy could guarantee it.