Radical Union of the Federation
Radikale Union der Föderation
Leader Lukáš Banik
Founded 21 April 1848
Headquarters Vienna
Ideology Radicalism
Political position Left-Wing
Official colours Red
Federal Assembly:
262 / 443
Federal Council:
28 / 56

The Radical Union of the Federation is a leftist political party in the Danubian Federation. Until recently, the RUF was the largest party in the country, representing the radical, leftist liberal, and Socialist ideologies in the Federation. It rose to prominence during the turbulent decade of the 1850's, after arising out of leftist defectors from the prevailing Liberal party, including one of its longest-serving members never elected to President, Crepko Obradovic. This party, although originally small, became the governing party of the Federation for over two decades, to the extent that some complained that this made Federal politics "boring". Eventually it declined rapidly in influence, although it is seeing a revival in support after the Lilic years.

The emergence of Archduke Franz Ferdinand and the establishment of a strong Imperialist movement around him, in conjunciton with the rise of the DRSL by Alexander Sik, dissatisfied with the more moderate policies of Lukas Banik, lead to a second, more pronounced decline in the party following 1886. Following the 1887 Mid-terms (and the loss of majority party in the House of Deputies), and in light of the DRSL's emergence, the Radical Union was formally renamed the United Progress Party at the 1889 Party Convention.