My understanding is that the facade has been in place since 1789, when the first republic was overthrown in a counter-revolution.

The Plan for the Overthrow. When the conspirators in Philadelphia adjourned in September, 1787, a complete plan for a new government to overthrow the First Republic came out of the secret session, and was presented to the public. It was not a plan for open dictatorship or monarchy, but compromised by having a form of government which was externally democratic and similar in general appearance to some of the state governments, yet enough power was centralized at a single point to enable one person to take over complete control whenever desired. Even so, three members of the secret session actually refused to sign the document, apparently on the grounds that too much concession to democracy had been made.

The "Federal Constitution," as it was called (in contrast to the existing constitution, known as the "Articles of Confederation") bristled with declarations of authority and bans and prohibitions at every point, especially where the States or Congress were concerned. The Congress of the proposed new government was hamstrung by being divided against itself, in order to make it easy to deadlock whenever the proposed two Houses should disagree on anything. A central executive authority was created, in the hands of a single person, called "President of the United States," after the title of the nominal head of the First Republic; but the difference was that while, in the First Republic, the President was merely a presiding officer with no personal power, under the proposed new system the President, contrary to the implication of the title, would do no presiding but could veto any actions of Congress, had complete control of the army and navy and held the purse-strings of the treasury. While under the First Republic the members of Congress were paid by the States that sent them, thus keeping them representatives of their constituency, under the proposed government to overthrow the First Republic, Congressmen would be paid by the Federal treasury (which was to be controlled by the President) and were not subject to recall during their terms, so that, once elected, they would for their entire terms be dependent on the President rather than on their constituents. One of the two Houses of the new Congress (called the Senate because, in line with the Cincinnati idea of gradual introduction of dictatorship on the lines of the ancient Roman Empire, Roman names were supposed to be in order) was arranged so that it would never change completely at any time, but one-third of the members would go out of office every two years, so that the majority would always be composed of members who were not dependent on the latest elections and whom the executive head (who was in closer contact with them than with the other House, according to the plan) could have reduced more to his will, especially through continued control of the purse-strings. In addition, the President, with an almost complete veto power over Congress, and with the duty of giving them an annual program of recommendations as to what would be expected of them in the way of legislation, would, it was expected by those who drew up this plan, be in a position to force any sort of legislation he wanted, in spite of the mandates of the States or the individual opinions of the members of Congress.

https://www.sidis.net/TSChap27.htm