In 1956, he ran on the Democratic and Liberal tickets for U.S. Senator from New York, but was defeated by Republican Jacob K. Javits. Like his father, Wagner was aligned with Tammany Hall for much of his career. However, when he sought a third term in 1961 Wagner broke with Carmine DeSapio and won the Democratic primary anyway, despite a challenge from Tammany's candidate Arthur Levitt Sr. A Democratic Mayor not aligned with Tammany was a new development and marked a milestone in the decline of traditional clubhouse or machine politics in New York City.