A rare debate factor: Both Harris and Trump have a White House track record

Tuesday's presidential debate marks a rare historical moment in that it pits against each other two candidates with significant track records in the White House.

That "political baggage" can be a curse for the candidates, according to experts who've studied debates, but also a blessing, depending on how it's portrayed and defended.

When they square off in the ABC News debate in Philadelphia, both Vice President Kamala Harris and former President Donald Trump will need to walk a fine line between affirming what they consider their successes during their administrations. And in Harris' case, that includes both supporting -- and separating herself -- from President Joe Biden's record, while also offering what she calls a "new way forward."

"The question the candidates face is how much credit do you take and what effects will that have on gaining more votes from undecideds," Kathleen Hall Jamieson, the director of the Annenberg Public Policy Center at the University of Pennsylvania told ABC News.

The history of sitting VPs on the debate stage

This will mark only the fourth election cycle that a sitting vice president will take part in a presidential debate.

Aaron Kall, director of the University of Michigan's Debate Program, told ABC News that in all of those previous cases, while the vice president was a candidate at the top of the ticket following very successful two-term presidents, it didn't guarantee victory.

Only one of those sitting vice presidents, George H.W. Bush, went on to win the White House.

The ABC News presidential debate will take place on Sept. 10 at 9 p.m. ET and air on ABC and stream on ABC News Live, Disney+ and Hulu.

"Some of the reasons incumbent vice presidents have tough times is because when it's three terms in a row of the same party, voters get fickle with that and want change," Kall said.

Kall said that vice presidents have to toe the line between repeating the rhetoric and plans that the incumbent has set forth and laying a foundation for their own vision.

Experts cited Vice President Al Gore's 2000 campaign as a prime example of that struggle -- and how that strategy can backfire.

Gore went into the election in the aftermath of President Bill Clinton's Monica Lewinsky scandal and aimed to distance himself from that by focusing less on Clinton's record, according to Jamieson.

The problem was that despite the scandal, Clinton's policies and record, especially when it came to the economy, were well-liked by voters and Gore failed to acknowledge that or run his campaign by capitalizing on that, Jamieson said.

"Gore might have been elected president had he not run away from the Clinton record," she said.

Harris faces opportunity, risks

After Harris assumed the lead of the Democratic presidential ticket in July, she inherited a host of advantages and risks going into her first matchup against Trump, according to the experts.

For starters, she is running in the rare occasion where a sitting president declined to run for a second term and does not have the near decade of standing that other sitting vice presidents had when they ran for office, according to Kall and Jamieson.

Although Biden's approval ratings were low prior to his exiting the race, many of his policies and actions were popular among Americans, according to Kall. Harris has already taken advantage of that by touting the success on the campaign trail such as the bipartisan infrastructure bill and the CHIPs bill.

She campaigned with Biden on Labor Day touting the administration's pro-labor policies.

At the same time, Harris has to deal with the shortcomings faced by the administration such as tackling rising prices and the immigration issue, according to experts. Harris has begun to address those concerns by presenting her own policy differences, such as her proposed change to a Biden plan that would tax capital gains at a lower rate than he proposed.

"She doesn't want to say she wants to continue the same policies as Biden, she needs to look forward to the future and set her own voice," Hall said. "She'll likely be preparing her debate in a similar way."

Kall noted that Harris also has the bigger advantage on her side: the split-screen with her older opponent. Biden took a major hit during the last debate because he appeared to be less tuned-in to the questioning, which gave weight to critics who contended the president was not fit for office.

Harris, who is 17 years younger than Trump, will likely try to use Trump's age to her advantage.

"Being of a younger age, being of a different generation, and her personal backstory … all of those things will allow her to keep her distance from both Trump and Biden on stage," he said.

Kall noted that the last-minute change to the ticket gave Harris' campaign less time to prepare for the debate, and, more importantly, less time to follow up on any mistakes or successes from the matchup.

"Timing is a premium and here because Harris is less defined and not present in this situation, how she does in those 90 minutes will show people how she can handle the job," he said.

Trump has to contend with his record

Trump is one of the few former presidents to run for re-election after being voted out. Grover Cleveland is the only president to win a second term in office after losing his bid for re-election in 1888.

Since the start of the 2024 campaign, Trump has been touting his record during his time in office while also going on the attack against Biden, Harris and the Democrats.

Jamieson said Trump's argument is similar to the often-repeated question "Are you better off than you were four years ago?" however, that question isn't necessarily a boon for either side.

"The Democrats want you to remember the pandemic and Republicans want you to remember the economy. And in both cases there are reasons to vilify the candidates on their past," she said.

The former president is coming into Tuesday's debate with more experience than Harris, as he has taken the presidential debate stage six times over the last eight years. Harris has not been in a debate since the 2019 Democratic primary.

Trump has continually bashed Biden and Harris over the administration's handling of the U.S. withdrawal from Afghanistan in 2021 and rising prices throughout his campaign stops, including a controversial visit to Arlington National Cemetery last month.

"A lot of Trump's debate performances have been similar to his rallies so I expect Afghanistan to come up in the next debate," she said.

Kall also predicted that Trump would bring up Biden and try to make voters believe that he and Harris are fully aligned in their policies.

"I think he'd prefer that he'd debate Biden a second time, but harping too much could turn off independents who want to move on," he said.

Trump's record has the most baggage of the two candidates from his two impeachments, the criminal conviction in New York and three outstanding indictments supersede any of his actions while in office, Jamieson said.

"There are some legacies that are carrying through and Trump is going to bring them in," she said. "The issue is how much that is brought up in the debate and how voters view his responses."

Ultimately, the experts said, the issue over the candidates' White House records will matter most to the key group of undecided most looking at the demeanor and how they handle policies that matter to them the most.

"The election is going to be close and those undecided voters in the handful of states will be key states," Hall reiterated. "They all certainly know Trump and Harris' past but they're going to be focused on what they will do going forward."