Section 128 of the Constitution specifies that alterations to the Constitution cannot be made without a direct public vote. A bill containing the amendment must first be passed by both houses of parliament or, in certain limited circumstances, by only one house of parliament. If the bill has only been passed in one house, the Governor-General must, under the "deadlock provision" of section 128, then decide whether or not to submit the referendum to the people. By convention, this is done on the advice of the Prime Minister. Since the Prime Minister normally controls the House of Representatives, the effect of this convention is to make it virtually impossible for a referendum to be put to the people if approved by the Senate, but not the House. In 1974, four proposals were put to the people by the Whitlam Government without the support of the Senate. Two of the four proposals had been twice rejected by the Senate, a third had been rejected once and failed to pass a second time, the fourth had been twice amended by the Senate.