> What are the legal protections of a “pledge”?

To answer that question is to first agree upon the legal definition of "pledge":

  pledge
  
  v. to deposit personal property as security for a personal 
  loan of money. If the loan is not repaid when due, the 
  personal property pledged shall be forfeit to the lender. 
  The property is known as collateral. To pledge is the same 
  as to pawn. 2) to promise to do something.[0]

> A pledge is a public commitment or statement of intent, not a binding legal contract.

This very well may be incorrect in this context and serves an exemplar as to why relying upon statistical document generation is not a recommended legal strategy.

0 - https://dictionary.law.com/Default.aspx?selected=1544

Congress could pass a new law requiring it, of course, but I think we all understand that this would not accomplish the administration's real goal of letting Trump prove he's the specialest boy and everyone has to give him what he wants.

That's the boring part until you look at what they're promising to do.

It's not as if existing data centers were getting power by sending a masked rogue to climb the utility pole, tap the lines and bypass the electric meter. Paying for electricity is the thing they were going to do anyway.

Likewise, paying for "new generation capacity" is the thing they were probably going to do regardless, because colocating large data centers with power plants saves the expense of power transmission which lowers their costs.

And as the article alludes to, the real question is when? In general you can build a data center faster than you can build a power plant, which is exactly the reason data centers can cause short-term electricity prices to increase. They temporarily cause demand to exceed supply until supply has time to catch up. So on the one hand the whole issue is kind of meh because it was only ever going to be a temporary price increase anyway, and on the other hand having them build power plants at the same rate anybody else is building power plants doesn't actually change anything or address the temporary shortfall. (If you really want to solve it, find a way to build power generation capacity faster.)

And then it doesn't matter if you can enforce the promise because they're just promising to do things they were going to do anyway.

One can do the former whilst repudiating the latter and remain logically consistent.