The power of the presidency has grown at the expense of Congress. President Donald Trump’s trade policy is the latest illustration of the fact that the chief executive in the United States is over-mighty. Unfortunately, the progressive left likes it that way.

The founders meant the presidency to be a powerful yet limited office. But President Woodrow Wilson viewed the Constitution’s separation of powers as a problem to be overcome by a powerful president, who would run the administrative state and inspire the people with his progressive oratory.

And since the start of World War II, in the name of national security or political convenience, Congress has sidelined itself by delegating power after power to the executive. This is not — strictly speaking — unconstitutional. But it traduces the spirit of the Constitution.

For example, the Constitution gives Congress the power “to regulate Commerce with foreign nations.” But as Trump’s imposition of tariffs shows, Congress has delegated much of this power to the president.

In 1962, the Trade Expansion Act (TEA) gave the president power to levy sanctions in cases where U.S. national security is (supposedly) at risk. But since national security is in the eyes of the president, the act amounted to an unconditional grant of Congress’ power to the White House. Congress repeated its mistake with Section 301 of the Trade Act of 1974, which authorizes the president to act against foreign violators — as he perceives them — of a trade agreement. The spirit of the 1974 act was right: We normally focus too little on enforcing our agreements. But in practice, the act was another unilateral giveaway of congressional power.

True, some presidents have used these powers for good. The TEA led to the most successful round of post-war tariff cutting. But these temporary successes came at the cost of the permanent diminution of Congress.

Trade is just one area in which the presidency has grown as the legislature waned. In the early 1950s, President Dwight Eisenhower fought off the Bricker Amendment, which sought to limit the power of the executive to make agreements with foreign nations.

For years, the amendment has been ridiculed: Ike described its progenitor, Sen. John Bricker (R-Ohio), as “almost psychopathic.” But today, Bricker’s concerns seem reasonable. Ike did not need to be restrained by Bricker, but not all future presidents would be as responsible as Eisenhower.

It is easy to say that the only person who needs restraining is Trump. That belief is wrong: President Barack Obama used the powers that Bricker sought to restrict to negotiate the Paris climate agreement and the Iran nuclear deal. And when Obama said in 2014 that “I’ve got a pen, and I’ve got a phone” — alluding to his intention to rely on executive actions if Congress didn’t do what he wanted it to — progressive Democrats cheered. If you condemn Trump but not Obama, you do not have a principled belief in the separation of powers.

Trump is creating the conditions for Congress to claw back some of its power, as shown recently by the Senate vote against his trade policy. But this is about Trump. There is no wider consensus that the executive is too powerful.

Nor are we likely to reach such a consensus, for a simple reason: ever since Wilson, the left has wanted a strong president, on the grounds that the best way for it to achieve its goals is to empower the president at the expense of Congress.

The enduring balance between the legislature and the executive in the United States can be restored and sustained only if the left accepts this balance is necessary. But that would require the left to give up on its strategy for achieving its goals.

The left hates Trump. But it doesn’t hate him that much.