Aged 81 and 78, Joe Biden and Donald Trump are both the subject of attacks on their cognitive abilities these days. Attacks which harm the president all the more as he appears more frail than his rival. His performance could confirm or refute doubts about his ability to lead his country for four more years. The same goes for the former president, who has recently made incoherent speeches. Ironically, Joe Biden could benefit from being portrayed as a president on the verge of senility. His opponents did not set the bar very high.

Chance favors Joe Biden on this key theme of his campaign. The debate comes four days after the second anniversary of the Supreme Court’s decision eliminating the constitutional right to abortion. The president will take the opportunity to recall Donald Trump’s role in this decision that a majority of Americans deplore and which is leading to horror stories in several states where abortion has been banned or access to it restricted. He will also criticize his rival for endangering access to the abortion pill and in vitro fertilization. His rival will argue that these questions are a matter for the States.

Donald Trump will respond with his own horror stories on his favorite subject. In recent days, he has focused on crimes committed by illegal immigrants, including the murder of a mother of five children. And he established a false link between these crimes and a new policy from Joe Biden that will allow illegal immigrants married for at least ten years to American citizens to obtain permanent residence. The president will respond by recalling in particular the pressure exerted by his rival on Republican parliamentarians to prevent the adoption of a bipartisan bill aimed at securing the southern border.

One of the unknowns of the debate is how the candidates will react to the rules announced by CNN, broadcaster of the event. Will the absence of an audience to applaud his lines cool Donald Trump? Will muting his microphone during Joe Biden’s speeches really prevent him from interrupting? Ultimately, these rules could help the former president project a more… presidential image, which would advantage him in the eyes of independents, the debate’s key audience. Another unknown: Donald Trump’s reaction to the moderators, Dana Bash and Jake Tapper, whose impartiality he has questioned in recent days.

The 90-minute debate will take place more than four months before the presidential election, rather than in late September or early October, as is customary. We can therefore wonder what will remain when voters make their choice. That said, a killer formula, a major gaffe or an unexpected performance could make an impact and reorient the race for the White House. Discussions on the economy, the dominant concern of voters, will also play a determining role in the impact of the debate. For the moment, voters trust Donald Trump more than Joe Biden on this subject.