Answer: William Jennings Bryan
Context/details:
William McKinley was the Republican candidate in 1896. William Jennings Bryan was the Democrat candidate. McKinley got 7,104,779 votes in the popular vote, and 271 Electoral College votes. Bryan received 6,502,925 popular votes, netting 176 Electoral College votes.
According to 270 To Win, the 1896 presidential election is considered "to be one of the most dramatic and complex in American history." In 1896, there were 447 Electoral College votes, with 247 needed to win. McKinley carried the states of the Northeast and the Midwest. Bryan won Southern states as well as most states in the West, with the exception of Oregon and California, which went to McKinley. [Oklahoma, New Mexico, and Arizona were territories at that time, not yet states.]