Bryan/Boies, though I should note that Watson was a massive racist and anti-semite IRL.
Oddly enough at this time though, he was one of the leading proponents of poor black and white cooperation. He thought at the time that it was more important for the poor to be united against the rich than for the whites to be united against minorities... He did change those views later though.
I think he changed his views around about the time the Populists collapsed as a political force. He really went firebrand on it during the Mary Phagan murder trial where he called for the lynching of Leo Frank.
If the Populists are not collapsing as a political force, it's possible Watson (incidentally, Watson is my last name, so I always feel weird typing it out when referring to someone else) never changes his views.
Poll
Vice President Adlai E. Stevenson (D-IL)