William H. Seward
The Republican Party had been founded in 1854, in reaction to the Kansas-Nebraska Act. Its anti-slavery stance was attractive to Seward, but he needed the Whig structure in New York to get re-elected. In September 1855, the New York Whig and Republican parties held simultaneous conventions that quickly merged into one. Seward was the most prominent figure to join the new party, and was spoken of as a possible presidential candidate in 1856. Weed, however, did not feel that the new party was strong enough on a national level to secure the presidency, and advised Seward to wait until 1860. When Seward's name was mentioned at the 1856 Republican National Convention, a huge ovation broke out. In the 1856 presidential election, the Democratic candidate, former Pennsylvania senator James Buchanan, defeated the Republican, former California senator John C. Frémont, and the Know Nothing candidate, former president Fillmore.
Puerto Rico Republican Party
Once the Spanish–American War ended in 1898, a wing of the Autonomist Party, an old party from Spanish colonial times, founded The Republican Party on July 4, 1899. This new party favored joining the United States as a federated state and was led by Dr. José Celso Barbosa. The party was ideologically conservative and was seen as representing the island's large sugar industry.