"After weeks of consideration and hundreds of conversations with constituents, I have come to the conclusion that Joe Biden is no longer the best person to make that case," Landsman wrote on X.
Landsman added that it is time for Biden to step aside and allow a new leader to be nominated to effectively challenge former President Donald Trump and advocate for America's future.
US Representative Zoe Lofgren, in a separate letter to Biden, expressed respect for his work but voiced doubts about his chances of a positive outcome in the upcoming election, urging him to step aside for new leadership.
After Biden's disastrous debate performance on June 28, some politicians and journalists have said that the current US president should be replaced and that Harris is the most suitable replacement.
At the Democratic National Convention in August, theoretically, the party can nominate another candidate if Biden pulls out, but so far, the president has said he intends to go all the way.
On September 10, a second debate between Biden and Trump is scheduled, and the presidential election in the United States will be held on November 5.