EDITORIAL: Debate will set the tone for presidential campaign

Polls show that many Americans are not overly enamored of either candidate — which is precisely why both parties wanted no part of letting Robert F. Kennedy Jr. in the debate despite his double-digit support in many polls. But it also raises the stakes for Mr. Trump and Mr. Biden, particularly among vital swing voters.

Mr. Biden’s advancing age is of concern, and he no doubt will make a concerted effort to avoid gaffes and to appear mentally sharp and agile. It’s no secret that those in the Biden camp sought to stage the first debate so early in the process because they need as much time as possible to recast the image of a foundering president. But there are risks to that strategy. Any major stumbles could prove fatal to Mr. Biden’s re-election campaign.

At the same time, Mr. Trump enters the debate having been found guilty by a New York jury of bookkeeping crimes. He faces other pending legal difficulties. Expect Mr. Biden to emphasize these points, along with the Jan. 6 incident, ad nauseam on Thursday night. Mr. Trump’s ability to deflect such criticisms without sounding defensive and petulant will go a long way toward ensuring that his opponent’s less-than-stellar record on inflation, immigration and other issues remains front and center.

Regardless of what happens Thursday, the partisans on either side will not be swayed. The winner in November will be the candidate who can attract the majority of independent voters to his side, particularly in swing states such as Pennsylvania, Michigan, Wisconsin, Arizona and Nevada. This could be a challenge for both candidates.

Mr. Biden entered office promising to “unite” the nation. He failed miserably in that regard. The president has made virtually no effort to compromise or reach across the aisle, and he routinely vilifies his political opponents. Kowtowing to the radical hard left is no way to generate support outside the coastal elites.

Mr. Trump has a fiercely loyal following, but he needs to attract moderate voters to push him across the finish line. Since he entered politics almost a decade ago, however, he has preferred to play to his base rather than lay the groundwork for expanding his support. Polls do show him making headway with Hispanic and Black voters, a warning sign for Democrats.

One debate does not a campaign make. But Thursday’s event will set the tone for the next four months and could also have a ripple effect down the ballot. Mr. Trump will try to stick to the issues. Mr. Biden will try to stick to Mr. Trump. Neither candidate can afford to blink.