A change of heads at the Treasury Department in March 1865 proved the occasion for a change of course in American monetary policy. New Secretary of the Treasury Hugh McCulloch not only declared himself sympathetic to the banking industry's desire for restoration of a gold-based currency, but he declared the resumption of gold payments to be his primary aim. In December 1865 McCulloch formally sought approval from Congress to retire the greenback currency from circulation, a necessary first step towards restoration of the gold standard. In response, Congress passed the Contraction Act, calling for the withdrawal of $10 million in United States Notes within the first 6 months and an addition $4 million per month thereafter. Substantial contraction of the physical money supply followed.