"I will do everything I can to get the president re-elected," Sanders said in an interview with The Associated Press.
According to him, the United States now does not need ex-President Donald Trump "or another right-wing demagogue."
He also ruled out the possibility that he would run for office himself.
Earlier, The New York Times, citing AP-NORC survey data, reported that Biden needs to talk openly about his health with voters during the upcoming presidential election.
In March, Biden said he had undergone surgery to test whether he had a brain.
He noted that he needed urgent surgery because of the aneurysm, but could not get to the hospital due to bad weather conditions.
As a result, the American leader was taken to a medical facility with the help of the fire department.