After the dissolution of Barebone's Parliament, John Lambert put forward a new constitution known as the Instrument of Government, closely modelled on the Heads of Proposals. It made Cromwell Lord Protector for life to undertake "the chief magistracy and the administration of government". He had the power to call and dissolve parliaments but was obliged under the instrument to seek the majority vote of the Council of State. However, Cromwell's power was also buttressed by his continuing popularity among the army, which he had built up during the civil wars, and which he subsequently prudently guarded. Cromwell was sworn in as Lord Protector on 16 December 1653.