Under the 1977 Political Reform Act, the Spanish Cortes were envisaged as a provisional legislature that was to approve a new constitution in a short timespan. Initiative for constitutional amendment belonged to the Congress of Deputies, as well as to the Government. Constitutional bills required to be passed by an absolute majority in both the Congress and Senate. If the Senate rejected the bill as passed by Congress, discrepancies were to be submitted to a Mixed Commission and, if the deadlock persisted, a joint sitting of both Houses would convene as a single legislative body in order to resolve on the issue by an absolute majority. Voting for the Cortes was on the basis of universal suffrage, which comprised all nationals over twenty-one and in full enjoyment of their civil and political rights.