Impoundment.
This was a presidential power dating from the early days of
Constitutional governance in the US through 1974, when provisions
of the Impoundment Act of 1974 made it almost impossible for a
President to not spend appropriated funds.
Thomas Jefferson in 1801 is the first President to impound
funds, refusing to spend monies appropriated by Congress. his power
was used by Presidents until the end of the Nixon
Administration.
The Impoundment Control Act of 1974 provides that a President
may propose the rescinding of specific funds, but that rescission
must be approved by both the House of Representatives and Senate
within 45 days.
However, since there is no requirement for Congress to vote on a
rescission request. Without a requirement to vote on the
rescission, Congress has effectively removed the Presidential
impoundment power since Congress has ignored the vast majority of
such Presidential requests.
In 1996, Congress sought to grant the President a "line item
veto"; the ability to "veto" or impound approved Congressional
spending by vetoing a specific budget line items. Unfortunately,
this ran afoul of the Presentment Clause of the Constitution, and
the Supreme Court struck down the "line item veto" in 1998.
