Soon after two overheated Ohio Republicans stood chest-to-chest trading taunts on the debate stage in 2022, Donald J. Trump watched a video of the viral clip and raised an eyebrow.
But it was the composed reaction from a third candidate on the stage that night, J.D. Vance, that helped win over the former president and secured a race-changing Trump endorsement for Mr. Vance in Ohio’s Senate primary.
Mr. Trump is thinking about debate performances once again as he considers whom to pick as the Republican vice-presidential nominee, according to three people who have spoken to the former president.
As he weighs the pros and cons of candidates, Mr. Trump has sought advice on who would be best to help raise money and who would be the most disciplined campaigner. A third factor, the three people say, is who matches up best on the debate stage against Vice President Kamala Harris, a seasoned politician and former prosecutor.
Measuring candidates by debate experience would appear to give at least a nominal edge to Mr. Vance. Now a U.S. senator, Mr. Vance is a leading contender to be Mr. Trump’s running mate and his debate skills have been praised by the former president.
But, like most of his metrics, there is much for Mr. Trump to consider.
Debates have long been of outsize importance to Mr. Trump, who has made clear both publicly and privately that he might not have won the White House in 2016 without them. Even eight years later, Mr. Trump has waxed nostalgic about his 2016 performances at least a dozen times during rallies and interviews since September.
Just last week, when asked about preparations for his June 27 debate against President Biden, Mr. Trump answered with a stroll down memory lane.
“Debates are interesting because I had never debated before and then I debated a lot in 2016,” Mr. Trump said on Fox News. “It’s been good for me — it’s been work — I think I won every debate.”
A Trump campaign spokesman declined to comment about the factors playing into his decision-making, saying that only Mr. Trump knows whom he will pick for a running mate.
Mr. Trump’s emphasis on debate performance underscores the central role that stagecraft is playing in his decision.
Foreign policy positions, cultural ideology and even political calculations over which contender may help the campaign win a battleground state have all, so far, taken a back seat to Mr. Trump’s focus on who will ably and effectively defend him on camera.
Other politicians and political strategists generally do not view debates as determinative as Mr. Trump does. But there is wide agreement that the skills and personality traits that make someone a strong debater — like quick wits and high charisma — often translate in other valuable ways on the campaign trail, such as easily connecting with donors or the ability to draw consistent applause from rally crowds.
“The opposite is also true,” said Kellyanne Conway, a former Trump White House counselor who helped prepare Mr. Trump for debates in 2016 and 2020. “If you’re not good in debates, you’re probably not great on TV and would have a hard time helping voters understand the rationale for your candidacy.”
For some potential running mates, past debate experience could hurt their chances.
Senator Tim Scott of South Carolina struggled in the Republican primary debates this year, putting in lackluster performances that were noted behind the scenes by Mr. Trump.
Ben Carson, the retired surgeon, was involved in one of the most awkward debate moments of the 2016 Republican presidential primary, when he stopped and waited just offstage after being announced instead of walking to his lectern.
The pros and cons for others are less clear.
Senator Bill Hagerty of Tennessee has been rising in Mr. Trump’s considerations, but he declined to debate any of his campaign opponents in the 2020 election.
Gov. Doug Burgum of North Dakota earned Mr. Trump’s respect in part by not criticizing the former president during the presidential primary debates and instead focusing on energy and the national economy.
Mr. Burgum was also largely overlooked by moderators, often because he was reluctant to attack fellow Republicans. Recently, he has displayed more aggressiveness with pointed criticisms of Mr. Biden.
Senator Marco Rubio of Florida suffered perhaps his worst public moment on a debate stage in 2016 — standing just a few feet away from Mr. Trump — when he seemed to malfunction amid criticism that he was too robotic.
During a heated exchange with Chris Christie, the former governor of New Jersey portrayed Mr. Rubio as a preprogrammed deliverer of well-polished applause lines. The Florida senator responded by repeating, nearly word-for-word, the same line from a moment earlier.
“There it is — the memorized 25-second speech,” Mr. Christie interjected as the crowd booed Mr. Rubio. The exchange sent Mr. Rubio’s popularity plunging, relegating him to fifth place in a crucial New Hampshire primary three days later and altering the dynamics of the Republican race.
But now, Mr. Rubio has become a close adviser to Mr. Trump and a more veteran politician. A strong debate performance in 2022 helped him win a third term in the Senate. More recently, he has relished the role as one of Mr. Biden’s fiercest critics on television.
Mr. Vance’s first foray into politics was his Senate campaign in 2022, when he made some remarks on the debate stage that Democrats would most likely resurface if he was picked by Mr. Trump.
During a primary debate, he said Representative Marjorie Taylor Greene of Georgia “did nothing wrong” by appearing at a white nationalist conference with an avowed white supremacist. In a general election debate, he backed a national ban on abortion after 15 weeks of pregnancy, a measure that not even Mr. Trump — who is responsible for the Supreme Court majority that overturned federal abortion rights — has been willing to support.
Still, Mr. Vance’s performance during the Ohio primary debates caught Mr. Trump’s attention, including one of the most-watched exchanges of the 2022 midterm elections.
As two of his primary opponents appeared ready to brawl, Mr. Vance watched wide-eyed. He laughed and reached for his microphone before thinking better of it and setting it down next to his lap.
But he quickly appeared frustrated as the confrontation unfolded in front of him.
He leaned back in his chair. He briefly inspected the back of his tie. He stood up and urged the instigator, Josh Mandel, a former state treasurer, to sit back down. “Goddamn, this is ridiculous,” Mr. Vance could be heard saying.
The moderator restored order and directed the next question to Mr. Vance, who instead admonished Mr. Mandel, a fellow Marine, for conduct unbecoming of a service member.
“Think about what we just saw,” Mr. Vance said to the crowd. “This guy wants to be a U.S. senator, he’s up here, ‘Hold me back, hold me back, I got two tours in the Marine Corps.’ What a joke. Answer the question, stop playing around.”
Mr. Vance won a straw poll of debate attendees, just as he did after two other Republican primary debates. A headline about those straw polls from Breitbart News made its way to the desk of Mr. Trump.
Three weeks later, Mr. Trump endorsed Mr. Vance, saying in a statement that “J.D. is the most likely to take out the weak, but dangerous, Democrat opponent.”
“J.D.,” Mr. Trump added, “will destroy him in the debates.”
