The Constitution, not that it seems to matter much these days, could not be clearer. Congress possesses the power of the purse. It alone controls how much of taxpayers’ money to spend, and on what. Spending is paramount among its enumerated powers: “No money shall be drawn from the Treasury, but in consequence of appropriations made by law.”

The president’s job is to “take care” that these laws are “faithfully executed.” That means overseeing the spending of the money that lawmakers have appropriated.
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Trump’s nominee to take the helm at OMB permanently, Russell Vought, ... believes the Impoundment Control Act, the 1974 federal law outlining how the president and Congress should handle spending disputes, is an unconstitutional encroachment on presidential power.
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Trump, during the campaign, pledged to “do everything I can to challenge the Impoundment Control Act in court, and if necessary, get Congress to overturn it.”

The Impoundment Control Act was the outgrowth of a series of spending disputes between President Richard M. Nixon and Congress. Among other things, Nixon refused to spend merely half the money allocated to sewage treatment after Congress overrode his veto of the Clean Water Act — how quaintly targeted, in light of Trump’s broad order.

Nixon was forced to resign as President. We can hope the same happens to Trump