Biden Will Pass the Torch to Harris in His Convention Speech

President Biden will headline the opening night of the Democratic National Convention on Monday with a valedictory speech that was supposed to have supercharged his final push for a second term but instead will serve as an opportunity to pass the torch to Vice President Kamala Harris.

Aides say Mr. Biden will use the speech to argue that Ms. Harris is the best person to carry on his legacy now that he is no longer in the race. Her candidacy as the party’s standard-bearer, he will argue, is the natural result of the choice he made four years ago to place her just a heartbeat away from the presidency.

That is not the case he expected to be making just over a month ago, before his stunning political demise following a debate performance in June that raised doubts about his age and vitality. Mr. Biden and his top aides, including Mike Donilon, his chief strategist, have spent the last several days reworking the speech for the new moment.

Mr. Biden will make only a brief appearance at the political celebration. His speech, which has a place of honor as the final one of the night, will begin just before 11 p.m. Eastern time. Around midnight, he and Jill Biden, the first lady, will fly to California for the start of a two-week vacation that will keep him out of the spotlight as Ms. Harris formally assumes her place as the new face of the Democratic Party.

The president will deliver his address to a convention hall filled with delegates who had been among his strongest supporters when he was a candidate. Organizers, who are decorating the hall with digital banners displaying common Bidenisms like “spread the faith,” expect an outpouring of affection for the 81-year-old president as he departs the stage.

But some are also bracing for