It is false that the Bull Moose Party took so many votes from the Democrats in the 1912 presidential election that the Republicans won.
In 1912, the Bull Moose Party was a dissident party that decided to support former US President Theodore Roosevelt for the 1912 election. This decision, of course, affected the Republican party. These factors helped Democratic candidate Woodrow Wilson to win the 1912 election. Years later the Moose Party disappeared.
