Serving a renewable five-year term, the president of the Commission oversees meetings of the College, decides on the distribution of portfolios, represents the Commission in dealings with other EU institutions, represents the EU at meetings with national governments and their leaders, and is generally responsible for ensuring that the Commission gives impetus to the process of European integration. In these areas, the president has the same executive function as the president of the United States, since 2010 even giving a similar "State of the Union" speech to the EP in Strasbourg. Still, Commission presidents have only a fraction of the powers of a U.S. president, and in some ways have the same status as nineteenth-century U.S. presidents, who had less of a role in government than either Congress or the states and were more clearly executives rather than leaders. However, the presidency of the Commission took on a new and more forceful character from the mid-1980s onward thanks mainly to one man: Jacques Delors.
There's probably more than one answer to this, but as an outline
- Intra-party politics on the nomination of the presidential candidate often resulted in weaker candidates in the 19th century; the famous smoke filled back rooms... which often enough nominated someone convenient for the party leadership.
- Presidential power has often increased in times of crisis such as the Great Depression and the World Wars.
- A more sustained process is the accumulation of powers delegated by Congress directly and those that were just self-asserted by the presidency. A history of Executive Orders is insightful in this respect. A theory is that this accumulation of power in the executive is inevitable, because in order for Congress to get something implemented, it needs the executive:
Obviously, talented and ambitious presidents have pushed the boundaries of the office adding new powers that were seldom surrendered by their successors. But, what made this tactic possible was the inherent constitutional imbalance between the executive and Congress. Presidential power has grown less because of the leadership styles of particular presidents, and more because the Constitution puts Congress at an institutional disadvantage and provides the president with an institutional edge.
For example, presidents derive power from their execution of the laws. Decisions made by the Congress are executed by the president while presidents execute their own decisions. The result is an asymmetric relationship between presidential and congressional power. Whatever Congress does empowers the president; presidential actions, on the other hand, often weaken Congress. If it wishes to accomplish any goal, Congress must delegate power to the executive. Sometimes Congress accompanies its delegation of power with explicit standards and guidelines; sometimes it does not. In either eventuality, over the long term, almost any program launched by the Congress empowers the president and the executive branch, more generally, whose funding and authority must be increased to execute the law. In effect, every time Congress legislates it empowers the executive to do something, thereby contributing, albeit inadvertently, to the onward march of executive power.
- The turning point is often thought to have been Teddy Rosevelt:
“[Roosevelt] was the first president who asserted a broad scope of inherent presidential authority,” says Kenneth Mayer, professor of political science at the University of Madison-Wisconsin and the author of With the Stroke of a Pen: Executive Orders and Presidential Power. “His view was ‘Unless I can’t, I will,’ while Taft’s [Roosevelt’s successor] was ‘Unless I can, I can’t.’”
“The constitution isn’t clear on what the president is authorized to do. The language is ambiguous and there are lots of gaps,” Mayer says. Just look at the wording on war: Congress has the power to declare war, but the president is named the Commander in Chief. Mayer also points to an argument between Alexander Hamilton and James Madison in 1793, when they fought over Washington’s ability to declare the U.S. neutral in a war between Britain and France. The men essentially wrote the Constitution, yet they disagreed about what it meant just a few years after they wrote it.
As for Taft, he undid several of Roosevelt’s executive orders. [...] Taft, who after his presidency would be named Chief Justice of the United States, responded that he was simply following the letter of the law. “We have a government of limited power under the Constitution, and we have got to work out our problems on the basis of law… I get very impatient at criticism by men who do not know what the law is.”
But for many presidents, executive actions are more like a loophole allowing them room for action—if they’re willing to exploit it. And Teddy Roosevelt most certainly was.
“Roosevelt showed that the executive role, if strategically used, can largely be the most powerful role despite a controlling bureaucracy,” writes political scholar Hilary Jan Izatt.
While the New Deal Era in the United States saw a great expanse in the powers of the Federal Government, and specifically the Executive Branch, it didn't stand alone. There are major milestones that empowered this populist shift.
In response to failed attempts to enforce an income tax on the populist, the 16th Amendment was ratified in 1913, with great populist fervor. This shifted more monies towards the Federal Government. Additionally in this populist wave, the 17th Amendment pass, transforming how Senators were assigned. With the shift to a popular vote instead of appointed by the State Legislatures the designed influence of the States on the Federal was reduced.
Further down the road, in the midst of the Depression, there was the transformative era 4 term run of FDR, with a stronger shift towards Federal Power. Chief among them was FDR's efforts to cajole the Judicial Branch to restrain his efforts, threatened to pack the court with sufficient judges favorable to his cause.
From that mindset, there was the shift in interpretation of the Tax and Spend Clause of the Constitution, leading to the construction of the now well bodied General Welfare Clause. In a minor aside amidst United States v Butler, which was decided against the Government, the Tax and Spend clause was transmogrified into a new, broader enumerated power. The Federal Government was now empowered to spend money as it willed. This great increase in Federal Power doesn't fully explain the growth in executive power.
The checks and balances of our Federal Government were designed on the axiom that individuals are greedy, and that its members would act with their enumerated powers to protect the same while checking against encroachment from the other branches. While a grand theory, it has proven to be a false assertion.
Congress is a cowardly branch; while there may be some members of integrity, by in large they enjoy the power of their office and spend much of their time trying to get re-elected than doing the Job. For that, they've learned over the decades that while doing something grand is a good way to stay in power, it entails a significant level of risk. Instead, they can do nothing offensive, while occasionally shifting funding back to their states via "general welfare" spending, to further enshrine their office. How is the government to run if Congress becomes risk adverse to passing actionable legislation? Through Intelligible Principle of course.
Intelligible Principle, (J. W. Hampton Jr. & Co. v US), is the legal fiction saying:
In a unanimous decision, the Court held that Congress, within "defined limits," could vest discretion in Executive officers to make public regulations and direct the details of statutory execution. The Court argued that the same principle that allowed Congress to fix rates in interstate commerce also enabled it to remit to a rate-making body under the control of the Executive branch.
Now, Congress can pass 'enabling legislation,' delegating great amounts of legislative power to Regulatory Agencies in the Executive Branch. Instead of politicians, answerable to the populace at the ballot box, governmental power becomes vested in bureaucrats of the Executive Branch.