FDR. He started big government, put innocent people in jail just because of their ethnicities (many Italian and German-Americans were also interned) and refused to do anything about the Holocaust.
FDR is complicated. Jews like to play the holocaust card, but his Jewish advisors also steered him in the wrong direction. He wanted to join WWII earlier but he had a lot of opposition.
Woodrow Wilson. He was definitely the biggest racist of the our presidents, and he was an anti Semite as well. Not to mention the founder of modern day progressivism.
I don’t think anyone comes close but I’d put Jummy Carter ym”s next.
John Kennedy, as bad as he was, became a leftist martyr as a result of his assassination. The left doesn’t tolerate pointing out Kennedy’s many faults.
Of course the left makes no similar veneration of Republican presidents who were assassinated.
Kennedy turned the tide on the cold war. And he kept patriotism high. It has been in free-fall since the 60s, with a few short-lived exceptions. Bush the Elder has very little accomplishments. Nixon Ford Carter may have been the worst decade ever.(But it is a confusing legacy.) Harding should be the worst.