President Joe Biden referred to Vice President Kamala Harris as “Vice President Trump” in response to the first question at a closely watched press conference Thursday, a little more than an hour after making a similar mistake with Ukrainian President Volodymyr Zelensky, who he referred to as “President Putin.”

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Biden is trailing Trump in several polls less than four months before Election Day, behind three by three points in RealClearPolitics’ polling average. The deficit has been fueled by an increasingly intense focus on Biden’s age and mental acuity from allies and critics alike, with 81% of his supporters in an ABC News/Ipsos/Washington Post poll believing he is too old to serve another term, which would end in 2029, when Biden will be 86 years old. Despite concerns about his mental acuity and calls from a growing number of Democrats to drop out, Biden has maintained he will see his reelection campaign through. Vice President Kamala Harris has emerged as Biden’s most likely replacement if the president drops out, though the exact process for replacing Biden at the top of the ticket remains highly speculative. Harris, however, performs similarly to Biden in the polls and, in some surveys, has lower numbers.

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