The only constraints are ecological . . . and they’re a doozy!
The Republicans wanted to spend $1 trillion more but the Democrats wanted to spend $3 trillion more. When they couldn’t compromise Trump decreed spending to make sure that people will see more in their pockets as Election Day approaches.
Naturally the pols will always want to spend more. They want people to like them and vote for them.
There used to be some constraint owing to the conception that budgets needed to be balanced. Keynesianism was a huge paradigm change because it authorized deficit spending. Naturally we then got more and more deficit spending. Some said (remember Ross Perot?) that there would be a build-up of debt that “our children will have to pay off.”
Modern Monetary Theory is a huge paradigm change because it authorizes printing money to pay the debt. We don’t have to pay, our children don’t have to pay, no one has to pay.
With such authorization there will be huge monetary printing. The MMT theorists say that a constraint would be unavailability of additional labor to employ or unavailability of additional material resources to allocate to production.
Please. The global labor force is six billion, of which billions are underemployed in industrial terms (i.e., they currently eek out a living doing subsistence farming but if money was available to employ them in the industrial system they’d be available to become participants). There’s really no constraint in regard to labor.
And are we really anywhere near running out of bauxite, iron ore, potash, graphite, or whatever the hell they mine to create all our stuff? or energy resources? No, we’re not.
Now that the pols have been authorized to print and spend they’ll feed more money to the industrialists to accelerate their already-rabid mining, building, harvesting, and consuming. There will be no more economic constraints.
The ultimate constraints will be ecological. I would say that when the planet is denuded, polluted, and toasting the pols will stop getting elected, but human civilization will start collapsing long before the last Election Day.