The Republican Constitutional Union (, UCR) was a Spanish political party created in 1893 by dissidents from the Possibilist Democratic Party (PDP) led by José de Carvajal y Hué, who opposed Emilio Castelar's decision to dissolve the PDP and join the Liberal Party following the 1893 Spanish general election. The party later joined with elements from the Progressive Republican Party (PRP) into the National Republican Party (PRN) in 1895.