The debate tonight between Vice President Kamala Harris and former President Donald Trump promises to be a pivotal moment in the 2024 election, as both candidates face significant challenges. The June 27 debate between Trump and President Joe Biden was a game-changer, laying bare Biden’s struggles with age and cognitive decline, which had long been denied by his administration and Democratic allies. That debate confirmed what many had suspected: Biden’s diminished mental acuity made him unfit to serve another four years, contradicting his 2020 promise to be a “bridge” president.
Biden’s refusal to step aside and the Democratic Party’s hesitance to challenge him put the party at risk, not only in the presidential race but also in congressional and state-level elections. The delay in addressing the reality of Biden’s condition left the Democrats scrambling to find a replacement before their national convention. Compounding the issue, the party prevented any discussion of alternatives to Harris, further limiting their options.
Harris herself has drawn criticism for her lack of engagement with the media, raising concerns about her transparency and ability to lead. Tonight’s debate will be her first real opportunity to face serious questioning one-on-one, and her performance could have a major impact on her political future.
For Trump, the stakes are equally high. While Biden’s cognitive struggles were the focal point of the June debate, Trump’s own erratic performance went largely unnoticed. His rambling and incoherent responses on key issues like abortion, immigration, and the fentanyl crisis revealed his own decline. For instance, Trump’s disjointed remarks on abortion included statements like, “The states are voting, which is what everybody wanted, including the founders, if they knew about this issue.” On immigration, his convoluted response praised Border Patrol’s support while losing focus on policy specifics. On fentanyl, he meandered through a discussion of drug-sniffing dogs and COVID-19 without addressing the crisis coherently.
Now that Biden is no longer in the race, Trump’s own mental and political decline is becoming harder to ignore. As the oldest presidential nominee in U.S. history, he faces increasing comparisons to Harris, who is nearly 20 years his junior. Trump has attempted to downplay concerns about his communication style, insisting that his so-called “weave” of topics is a deliberate and brilliant rhetorical strategy. However, his biographer, Timothy O’Brien, offers a different view, suggesting that Trump’s increasingly disjointed speeches reflect a man in mental and political decline.
The June debate underscored the difficult choice Americans face between two elderly candidates, both showing signs of cognitive decline. Ideally, both party establishments would have used this as an opportunity to reconsider their nominees. The Democrats moved first, as Biden’s decline was more evident, but now the spotlight is on Trump. If his performance tonight mirrors his lackluster showing in June—marked by personal attacks and a lack of substantive policy discussion—it will further demonstrate his unfitness for office.
Trump, of course, is unlikely to stand in stunned silence tonight. Instead, his age may manifest through confused thinking or juvenile antics. But if he falters, Republicans will have a final chance to reconsider their path forward, possibly paving the way for a younger, more coherent candidate. Should Trump refuse to step aside, much as he resisted leaving the presidency in 2021, party leaders will need to summon the courage to demand his withdrawal—just as Democrats ultimately did with Biden.
Joseph Bosco served as China country director for the secretary of Defense from 2005 to 2006 and as Asia-Pacific director of humanitarian assistance and disaster relief from 2009 to 2010. He is a nonresident fellow at the Institute for Corean-American Studies and a member of the advisory board of the Global Taiwan Institute.