Wikipedia says Harding was Republican. So I guess the list is for who won the plurality of Jewish votes.
Warren Gamaliel Harding (November 2, 1865 – August 2, 1923) was the 29th President of the United States (1921–1923), a Republican from Ohio who served in the Ohio Senate and then in the United States Senate where he protected alcohol interests and moderately supported women's suffrage. He was the first incumbent U.S. senator and (self-made) newspaper publisher to be elected U.S. president.
So now the question is what third party candidate took a significant amount of Jewish votes vs. the peanut farmer.