OPINION — In the late 1960s and early 1970s, there was a mournful chorus of warnings about the dangers of what historian and former John Kennedy aide Arthur Schlesinger called “The Imperial Presidency.”

Schlesinger wrote in 1973, as Richard Nixon twisted slowly, slowly in the wind, “The constitutional presidency — as events so apparently disparate as the Indochina War and the Watergate affair showed — has become the imperial presidency and threatens to be the revolutionary presidency.”

This deep concern about the unchecked powers of the modern presidency was not limited to Harvard intellectuals. In his own book, “The Twilight of the Presidency,” former Lyndon Johnson press secretary George Reedy used a King Louis XIV analogy: “The life of the White House is the life of a court. It is a structure designed for one purpose … to serve the material needs and desires of a single man.”

Compared to Donald Trump, the constitutional modesty of Johnson and Nixon represents the good old days. Instead of the Imperial Presidency, we now have the Gold-Plated, Monogrammed Presidency.

When William Fulbright, the chairman of the Senate Foreign Relations panel and an acerbic critic of LBJ’s war, held high-profile hearings in 1966 on Vietnam, the president did not try to block top officials like Gen. Maxwell Taylor from testifying. Johnson also had the grace to bow out of his 1968 re-election campaign when public opinion turned against him rather than darkly claiming, in Trump fashion, that the verdict was Fake News.

Nixon, not exactly a profile in virtue, voluntarily released his tax returns in late 1973 in an effort to appease the hounds of Watergate. When the Supreme Court unanimously ruled in July 1974 that Nixon hand over the White House tapes, the president reluctantly complied instead of holding a bonfire on the White House lawn.

After Nixon’s resignation, the nation was blessed with two presidents with appealing modesty about claiming imperial powers from the Oval Office. History may not lionize everything about Jerry Ford and Jimmy Carter (whom I worked for in the White House as a speechwriter). But both Ford and Carter, sometimes to their frustration, recognized Congress as a coequal branch of government.

The 21st-century erosion of congressional powers did not begin with Trump.

It is a constitutional embarrassment that American military forces are in combat in more than a dozen countries and battling terrorism in roughly 80 nations, all while operating under the hastily written congressional authorization approved after the 9/11 attacks. This is akin to the Doughboys going over to France in World War I because America declared war against Spain in 1898.

But the 45th president’s particular specialty is stiffing Congress as if the Senate and House were unpaid painting contractors at a Trump golf course.

Remember that Trump’s first presidential veto was a rejection of bipartisan congressional efforts to overturn his dubiously legal claim of an emergency at the Mexican border. Trump’s second veto: blocking a congressional drive to prevent U.S. forces from continuing to aid the Saudis in the civil war in Yemen.

Even more alarming is Trump’s cynical indifference to naming a permanent successor to Defense Secretary James Mattis, who was forced to resign nearly five months ago.

In this void — deliberately free of congressional oversight — power has flowed to John Bolton, Trump’s aggressively hawkish national security adviser. Depending on the week, Bolton seems poised to draw America into a military confrontation with either Iran or Venezuela. Presumably, Congress would learn of these hostilities via Trump’s Twitter account only after the shooting had begun.

This discussion of the Gold-Plated, Monogrammed Presidency began with foreign policy because it is important to stress that what is at stake is far larger than this week’s battles over the Mueller Report or Trump’s tax returns. The framers of the Constitution envisioned Congress having broader powers than merely naming post offices and rubber-stamping conservative judges.

Trump set a dubious precedent Wednesday morning with his overarching claims of executive privilege covering all unreleased aspects of the Mueller report and the background documents that accompany it. Sarah Huckabee Sanders — the first White House press secretary allergic to questions from reporters — said in a statement, “Neither the White House nor Attorney General [William] Barr will comply with Chairman [Jerry] Nadler’s unlawful and reckless demands.”

Somehow this does not sound like the sincere affection that Trump routinely directs toward Vladimir Putin and Kim Jong Un.

The party-line 24-16 vote Wednesday afternoon in Nadler’s House Judiciary Committee to find Barr in contempt of Congress was about as surprising as a nasty Trump tweet. Lurking behind all the predictable rhetoric is the unfortunate reality that the federal courts probably will end up defining the extent of presidential powers in the face of congressional subpoenas.

Maybe I am too pessimistic in this hyper-partisan era, but I feel far from certain that the Supreme Court’s unanimity in the 1974 Nixon tapes case will serve as the model for Trump’s 2019 battles over executive privilege.

“It’s Your Fight Too” was a World War II morale slogan later borrowed in politics by the 1988 Dick Gephardt presidential campaign. But these sentiments also apply to all members of Congress — even MAGA-hat-wearing Republicans — in the current battle over White House stonewalling.

Every Trump-era precedent may someday be invoked by a Democratic president. At that future moment in, say, 2021 or 2025, Republicans in Congress may be asking themselves why they were so timid in the face of Trump’s Gold-Plated, Monogrammed Presidency.