This intensely antagonistic election has shattered another quaint campaign ritual: the handshakes between opposing candidates’ family members before a debate.
At previous debates, former President Bill Clinton has shaken the hand of Melania Trump — and sometimes the hands of the children of Donald J. Trump — as part of the predebate protocol.
It provides the audience in the room, and the people watching at home, with a moment of graciousness and a touch of celebrity.
But for the final debate, Hillary Clinton’s campaign wants a different setup, according to two people with direct knowledge of the situation who requested anonymity to speak candidly about debate negotiations.
That’s because at the previous debate, on Oct. 9 in St. Louis, the Trump campaign had an elaborate plan to parade three women who accused Mr. Clinton of sexual assault and rape into the family seating area and force Mr. Clinton to shake their hands as he crossed the room.
Had the Trump campaign succeeded, Mr. Clinton would have come face-to-face with the women on national television, a potentially humiliating and excruciating encounter. However, the Commission on Presidential Debates intervened, and the women — Juanita Broaddrick, Paula Jones and Kathleen Willey — never came close to Mr. Clinton.
But the Clinton side is not taking any chances at the final presidential debate, on Wednesday night in Las Vegas, and has apparently gained approval of a different protocol for the entry of the candidates’ spouses and families into the debate hall.
The new arrangement calls for the candidates’ spouses to enter the hall closer to their seats, rather than crossing the room, and each other’s paths.
That would avoid any potential for confrontations, given Mr. Trump’s penchant for dramatic stunts.
On Tuesday, an aide to Mrs. Clinton declined to comment on the change, and aides to Mr. Trump did not respond to an email seeking comment.
It is possible, of course, that further negotiations could result in a different arrangement, if both sides agree, by the time the debate begins at 9 p.m. Eastern.
But the unease over how the candidates’ families interact echoes that of the candidates themselves. At the debate in St. Louis, in a striking departure from tradition, Mrs. Clinton and Mr. Trump did not shake hands at the start, though they did at the conclusion of the 90 minutes.
The Clinton campaign is bracing for other possible Trump surprises at the debate, which seem more likely as the Republican nominee slips further in the polls.
Mr. Trump’s aides are preparing him with a sharp escalation in attacks on Mrs. Clinton’s character and a focus on her health, according to a senior campaign adviser, who spoke on the condition of anonymity.
On Sunday, in a debate prep session at his golf club in Bedminster, N.J., Mr. Trump sparred with Gov. Chris Christie, who informally played the role of Mrs. Clinton, according to a second senior adviser, who also requested anonymity to share details of internal campaign activities.
Mr. Christie helped sharpen Mr. Trump for his last debate performance, helping him to more aggressively and coherently attack Mrs. Clinton over her use of a private email server, the adviser said. This time, Mr. Trump’s advisers are preparing lines related to Mrs. Clinton’s health, which Mr. Trump has sought to make an issue of after her bout of pneumonia in September.
At his rallies, Mr. Trump tends to highlight any time that Mrs. Clinton spends off the campaign trail. He has seized on her days off in the past week as evidence of frailty, though she used much of the time to prepare for the debate and hold private fund-raising events.
On Tuesday, according to a person briefed on the plan, Mr. Trump intends to bring President Obama’s half brother, Malik Obama, a Trump supporter, to the debate.
Aides to Mrs. Clinton, who seemed rattled but who did not flinch last time as her husband’s accusers sat in the debate hall, insisted she was prepared for whatever happens.
“Whatever scorched-earth tactics he has planned for the debate, we will be ready and she will be unfazed,” said Brian Fallon, a spokesman for Mrs. Clinton.