Progressive Party (United States, 1912)
The Progressive Party was a third party in the United States formed in 1912 by former President Theodore Roosevelt after he lost the presidential nomination of the Republican Party to his former protégé, incumbent President William Howard Taft. The new party was known for taking advanced positions on progressive reforms and attracting some leading reformers. After the party's defeat in the 1912 presidential election, it went into rapid decline, disappearing by 1918. The Progressive Party was popularly nicknamed the "Bull Moose Party" since Roosevelt often said that he felt "strong as a bull moose" both before and after an assassination attempt on the campaign trail.
Unionist Party (United States)
By 1860, the Whig Party was defunct. A group of former Whigs formed the Constitutional Union Party, with John Bell as candidate for President. Also as in 1850, ex-Whigs and anti-secession Democrats combined as "Unionists" to oppose secessionists in state elections, especially in Kentucky, Maryland, Missouri and Virginia, where the Republican Party label was still toxic. Bell's candidacy was ineffective, but the state strategy proved successful as the American Civil War began in 1861.