As Donald Trump moves forward, proving ever more his ability to alienate traditional Republicans and conservatives, and his racism, nativism, misogyny, and xenophobia leading to a likely low percentage among African Americans, Hispanic and Latino Americans, Asian Americans, Muslim Americans, Jews, Social Justice Catholics, women, college educated, environmentalists, gays, disabled, and every other conceivable group, the likelihood that he might be on the way to the worst possible major party candidate popular vote percentage since 1912 and 1924 seems a strong possibility.
In 1912, President William Howard Taft, challenged by former President Theodore Roosevelt and the Progressive Party, ended up third, the only time a major party nominee ended up other than first or second, and only received 23.2 percent of the vote, winning 2 states and 8 electoral votes, and Woodrow Wilson winning the election. TR as the third party nominee won six states and 27.4 percent of the total national vote that year.
Once we get past that unusual situation, the next worst performance by a losing major party candidate is John W. Davis , who lost to Calvin Coolidge in 1924 and won only 28.8 percent of the total popular vote, winning twelve states and 136 electoral votes. However, Progressive Party candidate Robert M. La Follette Sr won 16.6 percent of the vote in that election.
Next was James Cox, who lost to Warren G. Harding in 1920, receiving only 34.2 percent of the vote, winning eleven states and 127 electoral votes.
Next was Alf Landon, who lost to Franklin D. Roosevelt in 1936, winning only 36.5 percent of the vote, and two states and 8 electoral votes.
Next was George H. W. Bush who won only 37.4 percent of the vote in 1992 against Bill Clinton, but Ross Perot won 18.9 percent of the vote that year as an Independent nominee. Bush won 18 states and 168 electoral votes in that election.
Next on the list is George McGovern who won 37.5 percent of the vote in 1972 against Richard Nixon, winning only Massachusetts and the District of Columbia and 17 electoral votes.
Next is Alton B. Parker who won 37.6 percent of the vote in 1904 against Theodore Roosevelt in 1904, but also won 13 states and 140 electoral votes.
Barry Goldwater, losing to Lyndon B. Johnson in 1964, won only 38.5 percent of the vote, and had 6 states and 52 electoral votes.
Finally, President Herbert Hoover, losing to Franklin D. Roosevelt in 1932, had only 39.7 percent of the vote, and won 6 states and 59 electoral votes.
So nine times, a major party nominee since the Civil War has won less than 40 percent of the total national popular vote, but with three times, 1912, 1924, and 1992, being complicated by a strong third party vote.
Five of these candidates who won less than 40 percent of the vote were Republicans—Presidents Taft, Hoover and the first Bush, and also Landon and Goldwater.
The other four were Democrats—Davis, Cox, McGovern, and Parker.