If he returns to the White House, Trump will seek to resurrect authority that Congress stripped from the presidency almost a half century ago. 

What President Nixon squandered, his campaign promises, Trump will restore, namely the impoundment power. "A lot of you," the former president told a New Hampshire crowd Thursday, "don't know what that is." Indeed, few now remember it. 

Impoundment, if restored, would allow a president, in theory, to simply refuse to spend appropriations by Congress. More than just an avenue to cut spending, Trump sees that kind of authority as key to starving, and thus crushing, the so-called "deep state." 

But such a move would fundamentally alter the balance of power, and any effort to restore the long-forgotten authority virtually guarantees a protracted legal battle over who exactly controls the power of the purse. Trump welcomes that fight. Some budget experts believe he won't get anywhere.

Regardless, advisors close to the former president tell RealClearPolitics they are drawing up plans to challenge the 1974 Congressional Budget and Impoundment Control Act in court, and if that fails, to lean on the legislature to repeal it. The latter would require passing a law to surrender power, something lawmakers are loath to do.