WASHINGTON — Most Supreme Court justices on Monday seemed inclined to allow President Trump to tell a former Federal Trade Commission honcho that she’s fired, in a case that could dramatically expand presidential power over independent agencies.

Despite a statute insulating FTC commissioners from being fired without cause, the high court’s conservative majority seemed concerned that Congress had usurped too much executive power from the presidency with the formation of independent agencies.

“You’ve mentioned many times [that] you can just go to Congress to fix this. Well, once the powers taken away from the president, it’s very hard to get it back in the legislative process,” conservative Justice Brett Kavanaugh told an attorney for former FTC commissioner Rebecca Slaughter during oral arguments.

“Independent agencies shift power from the presidency to the Congress. Everyone recognizes that the Congress has more control over the independent agencies than they do over the executive agencies.”

At issue before the high court was Trump’s firing of Slaughter from her perch as one of five FTC commissioners in March.

The Federal Trade Commission Act stipulates that commissioners can only be ousted for “inefficiency, neglect of duty, or malfeasance in office.”

Multiple lower courts have ruled against Trump on the firing. But in September, the Supreme Court allowed Trump’s firing of Slaughter to take effect while it considers the case.

US Solicitor General John Sauer contended that the statute for the FTC and the fundamental structure of many independent agencies essentially encroach upon the president’s executive power.

Looming over that argument were concerns that Congress also delegated some of its legislative powers to independent agencies. Conservative Justice Neil Gorsuch mused that that dynamic might have to change.

“Is the answer, perhaps to reinvigorate the inherent intelligible principle doctrine and recognize that Congress cannot delegate its legislative authority,” Gorsuch pondered at one point.

“A lot of legislative power has moved into these agencies, but if now they’re in control by the president, it seems to me all the more imperative to do something about it.”

The last time the Supreme Court weighed in on the limits of the president’s ability to fire FTC commissioners was in Humphrey’s Executor v. United States in 1935.

The justices at the time unanimously found that presidents could not dismiss FTC commissioners over policy differences alone. But the conservative majority seemed unconvinced by the precedent.

“Humphrey’s Executor is just a dried husk of whatever people used to think it was,” Chief Justice John Roberts remarked Monday.

“[The FTC of 1935] has nothing to do with what the FTC looks like today,” he added. “It was addressing an agency that hadn’t very little, if any, executive power.”

For months, the Supreme Court has given Trump a string of temporary wins on the motions docket for many cases involving his attempts to fire high-level government officials. Monday’s arguments finally gave more insight into the majority’s thinking when it comes to a president’s ability to fire top personnel.

During arguments, conservative justices peppered Amit Agarwal, the attorney for Slaughter, with hypotheticals of Congress reworking agencies and splitting cabinet-level positions into commission-like structures to take the president’s ability to fire his top lieutenants.

At one point, Agarwal seemed taken aback by the tough questions he faced about the constitutionality of the Federal Trade Commission Act, pointing to prior precedent.

“We don’t need an abstract theory to tell us that the FTC Act is okay,” he argued. “It’s the other side that needs to give you a really compelling theory to explain why, in our view, 200-plus years of precedent and history need to be abandoned.”

All three liberal justices fretted about the implications of gutting the structure for independent federal agencies,

“Congress has given these agencies a lot — a lot of work to do that is not traditionally executive work, that is more along the lines of make rules when we issue broad delegations,” liberal Justice Elena Kagan said.

“If you take away a half of this bargain, you end up with just massive, uncontrolled, unchecked power in the hands of the president. And it’s really hard to affect both sides of this bargain because it’s already been done.”

While a majority of the justices seemed sympathetic to Trump in the FTC case, some outside observers surmised that it could hint at trouble for the president in his blockbuster tariff case that the high court heard last month.

“The more Justice Gorsuch speaks in the Slaughter oral argument, the more I think he’s a strong vote against tariffs,” conservative New York Times columnist David French observed.

“He’s wanting to jam the legislative *and* executive branches back into their constitutional boxes.”

A decision in Trump v. Slaughter is expected by the middle of next year.