Campaign advisers to Donald J. Trump, concerned that his focus and objectives had dissolved during the first presidential debate on Monday, plan to more rigorously prepare him for his next face-off with Hillary Clinton by drilling the Republican nominee on crucial answers, facts and counterattacks, and by coaching him on ways to whack Mrs. Clinton on issues even if he is not asked about them.

Whether he is open to practicing meticulously is a major concern, however, according to some of these advisers and others close to Mr. Trump…

Some of the advisers want to practice getting under his skin, as Mrs. Clinton did, to gauge his response, but they offered no details about doing so. Others wanted practice sessions built around the next debate’s format, a town-hall-style meeting, where Mr. Trump is likely to engage with undecided voters asking him questions and, at times, move from his chair to walk the stage. Mr. Trump has little experience with the format, which can be challenging for people who do not practice managing their body language and movements…

There were early efforts to run a more standard form of general election debate-prep camp, led by Roger Ailes, the ousted Fox News chief, at Mr. Trump’s golf course in Bedminster, N.J. But Mr. Trump found it hard to focus during those meetings, according to multiple people briefed on the process who requested anonymity to discuss internal deliberations. That left Mr. Ailes, who at the time was deeply distracted by his removal from Fox and the news media reports surrounding it, discussing his own problems as well as recounting political war stories, according to two people present for the sessions.