The Speech Joe Biden Has Been Preparing For His Entire Life

His belief in his own skills as an orator — his ability to persuade, to move, to own the room — has been a through-line of his public arc, often leading him to seek his own counsel despite any guidance he might absorb from advisers.

One former Senate speechwriter recalled Mr. Biden describing their working relationship like this: “I’m going to compare you to a golf coach,” Mr. Biden told the aide. “If you try to change my swing, we’re not going to get along.”

Matt Teper, a top Biden speechwriter during his vice presidency, suggested Mr. Biden’s attention to detail could border on the obsessive. “You have an engaged principal,” he said. “You’ve also got someone who, on a word level, is caring about things that sometimes you’re like, ‘well, let’s leave the commas to me.’ But by and large, his engagement makes things better.’”

Mr. Teper predicted that the final edits on Thursday would be made as late as “an hour or two in advance” — or, perhaps, extemporaneously. “He will change one thing as he delivers it,” Mr. Teper said, “to make it better.”

Of course, Mr. Biden’s words have not always landed with care. His first presidential bid, for the 1988 Democratic campaign, ended in a hail of plagiarism accusations. His next one, 20 years later, reinforced perceptions of verbal recklessness almost immediately, when Mr. Biden gave an interview in which he called Mr. Obama, his fellow competitor, “the first mainstream African-American who is articulate and bright and clean and a nice-looking guy.”

When Mr. Biden became Mr. Obama’s vice president, his incaution by turns frustrated White House aides and cemented Mr. Biden’s standing as a kind of incorrigible tale-telling uncle, prone to exaggeration or profanity on a live mic. On the campaign trail this cycle, he often wandered off-script, into meandering asides, verbal missteps and the occasional inaccurate story that had to be walked back.