The Progressive Party of 1912 was an American third party. It was formed by former President Theodore Roosevelt, after he lost the nomination of the Republican Party to his former protégé, President William Howard Taft, who had since become his political adversary.
The new party was known for taking advanced positions on progressive reforms, and attracting some leading reformers. However it ran a full ticket and Republican politicians and political activists across the country generally refused to join. California was the exception, for the progressive element took control of the Republican Party in that state, and ran its leader Hiram Johnson as Roosevelt's running mate. It carried only eight states, enabling Democrat Woodrow Wilson to score a massive landslide in the electoral college, as well as control of both houses of Congress. Beset by factionalism and failure to win many offices, the party went into rapid decline by 1914 and virtually disappeared in 1916. One main result was that conservative elements took control of the Republican Party for decades. The reforms proposed by the party had all been under discussion for years.
The Progressive party was nicknamed the Bull Moose Party after journalists quoted Roosevelt saying that he felt "fit as a bull moose" shortly after the new party was formed.