Institutional power is more of an academic topic. Nonetheless, it has enormous ramifications. The current immigration debate is a great example of that. Despite the rhetoric around the DHS debate, America has never had a dictator president - the current president included. However, the fight for power in the separation of powers (i.e. How big should the presidency be?) is real. The DHS/immigration debate is an interesting look into that struggle.
Much of the modern presidency’s power stems from the type of actions we are observing in the immigration debate. Reinterpreting existing law, exercising discretion on the many responsibilities under the purview of the executive branch, or writing orders and directives, presidents have ample opportunity and authority to reshape national policy unilaterally. These actions pale in comparison to actually creating law, as Congress does, but they are important nonetheless. And while Obama’s immigration action falls within precedents set by former presidents, Congress is well within its constitutional rights to correct presidential overreach.
However, Congress rarely curtails presidential unilateral actions. There have been several attempts but few are successful. The best attempt was the 1974 Budget Control and Impoundment Act, establishing the modern budget process. After Nixon impounded congressionally appropriated funds, Congress established processes and deadlines to take back budgetary control. It also established a reconciliation process that could circumvent filibusters to restore budget harmony. That process could be used to respond to executive actions if those actions fail to follow congressional intent.
As we see today even Congress's most powerful tool cannot address executive action. It would take some creative legislative drafting in order to use reconciliation to reverse Obama’s immigration action, which prohibits provisions that have no budgetary effect. Which means today’s congressional stalemate boils down to one of two possibilities. Either it can’t be done or Republicans plan on using reconciliation -which only allows a limited amount of bills per year - for another purpose.
This is the problem Republicans currently face. They cannot circumvent the supermajority requirements of the process. Even if they could, there is no guarantee Republicans could find a Senate majority once the symbolic nature of the cloture vote was removed from the scenario. Should three moderate or border Republicans join Senator Dean Heller in blocking the bill, Congress’s response would still be deadlocked.
Historically Congress’s power has been hampered by its own processes and the political realities of forging majority coalitions. It’s often very difficult pass bills through both chambers. It’s particularly challenging to find majorities to challenge unilateral executive actions that fall within the previously accepted scope of executive authority. It’s nearly impossible to find a supermajority to do that. Without a Watergate-like scandal, where illegal actions clearly occurred, Congress rarely has the ability to tame America’s 80-year tradition of expansive executives.
The ambiguity of Article II means that presidential power open to interpretation, which is another way of saying that presidents' unilateral power is mostly anything that Congress has not expressly prohibited. Given the inherent difficulties of lawmaking and the supermajority processes that have always existed in Congress, historically those prohibitions have been scarce.
As Jon Bernstein points out, every modern president overreaches at some point. With a hamstrung legislative branch, that’s likely to continue.