For a while now, my internal model for the the balance of power between the executive branch and the legislative branch has been that the balance is mostly chosen and adjusted by the Supreme Court. The Supreme Court is a deliberative body and has the final say on a lot of similar issues. The court’s members are also chosen jointly by the executive branch and the legislative branch (although, the executive branch certainly has a bigger say), so it makes sense for the two branches to defer to the court on the issue of balance of powers. Opining on Charlie Savage’s Takeover, Stephen Griffin offers an alternative explanation
In Savage’s imperial narrative, power-hungry presidents seem to parachute in from outside the constitutional system promoting novel theories that have no true historical antecedents. But this ignores that such power would be hard to acquire and wield without the support of millions of Americans. While it may be hard for congressionalists to understand, many Americans do believe the president is head of the government and best able to respond to foreign policy crises.
I am skeptical of the idea that voters have preferences for how power is distributed among the branches. The balance of powers is a very esoteric issue, so I think voters are unlikely to care about it. Griffin also mentions elite opinions, which, I think are much more likely to care about the balance of powers, but elite opinions affect public policy in different ways than voter opinion (in ways which I don’t have a good internal model for). Consider elite opinions on farm subsidies. My impression is that there is basically a consensus that farm subsidies are bad, but we will probably continue to have farm subsidies for a long time.
Still, I read The Power of Separation, which is on the separation of powers, recently, and I got the impression that a lot of balance of powers issues are handled without court intervention.
I think if you wanted to make the judicial branch more responsible for the balance of powers, you would have to make it much easier for congress and the president to challenge actions taken by each other.
Addendum: Griffin also notes two interesting theories about political parties. First, Savage asserts that political parties in the American system “can make Congress behave more like a subordinate and deferential arm of the executive branch than like the independent and coequal institution the Founders intended it to be.” Second, Griffin asserts that “parties helped overly separate branches work together to create public policy.” Both interesting theories.