Biden also endorsed Vice President Kamala Harris in a follow-up statement.

“My very first decision as the party nominee in 2020 was to pick Kamala Harris as my Vice President,” Biden wrote. “And it’s been the best decision I’ve made. Today I want to offer my full support and endorsement for Kamala to be the nominee of our party this year.”

According to CNN, many of Biden’s opponents and some of his colleagues have been increasingly raising concerns about his stamina and mental capability. The 81-year-old’s debate performance on June 27 especially brought concerns for many viewers and political experts who noticed that the president was struggling to focus and speak clearly. Biden’s campaign tried to explain the poor performance, first saying that he was dealing with a cold, then stating the he had jet lag due to his recent international travel.

Biden appeared to be more energized when he appeared at a rally on the day after his concerning debate performance.

“I don’t walk as easy as I used to,” Biden said at the rally, per CNN. “I don’t speak as smoothly as I used to. I don’t debate as well as I used to. But I know what I do know: I know how to tell the truth. I know right from wrong. I know how to do this job. I know how to get things done.”

Still, Biden continued to face increasing pressure from Democrats and Republicans who were urging him to drop out of the race. Rep. Lloyd Doggett of Texas was the first member of Congress from Biden’s party who told the president to give up his candidacy, CNN reported. Biden, however, remained defiant. Speaking with ABC’s George Stephanopoulos on July 5, the President said only the “Lord Almighty” would persuade him to drop out.

Earlier this week, Biden announced that he has COVID-19, adding more fuel to the concerns about his long-term health. After Biden officially withdrew from the race on Sunday, Harris now appears to be set to face Donald Trump in the 2024 presidential race.