Not long ago, a friend was reciting things she needed to do before celebrating Passover with her family: preparing the ritual foods, doing something special for her grandchildren and making room for her daughter’s in-laws.

Exhausted by the list, she looked at me and said, “It’s not easy being Jewish.”

I know the feeling. I’m a Donald Trump supporter.

The president rarely makes it easy on the faithful, often testing his tribe through errant word and deed. Even on his best days, he manages to insert a hurdle or two or 10.

The James Comey affair is the perfect example. On substance, Trump made the absolute right call. Comey had to go, with his blunders on the Hillary Clinton case reason enough. And there were many others.

Yet being right isn’t enough in Washington, and being Trump raises the bar exponentially. The Democratic left and the media (I know, that’s redundant) get out of bed ready to pounce.

They don’t need facts to unleash their volcanic hatred of him. A juicy rumor and an anonymous source will suffice. Any mistake sparks talk of impeachment.

Some days, Trump gets the level of difficulty, telling Reuters about his first 100 days, “I thought it would be easier.”

Other days, he gets everything backward, making it hard for supporters to defend him and easy for opponents to attack. This is not merely annoying.

The exasperating pattern has been and remains the existential threat to Trump’s presidency, given his precarious public standing and his party’s narrow margin in Congress. He will not be able to deliver on his promises to revitalize the economy and rebuild the military unless he establishes wider support for his agenda and more trust in his judgment.

The task applies to politicians and ordinary citizens alike. Both need frequent reassurance he is up to the job.

The Comey uproar also proves something else: that a good idea, especially a big one, requires equally good execution. The bungled rollout undercut the bold logic of the decision, and the White House’s reaction to the ­reaction is a textbook case in how to make a problem worse.

Some examples: The bombshell firing caught everybody by surprise, including Trump’s team. Opponents quickly filled the vacuum with outrage, shaping the first news cycle and gaining ­momentum. Did his team expect universal cheering?

To compound the one-sidedness, Comey was in Los Angeles when the dismissal letter was delivered to his Washington office. The sloppy White House staff work meant Comey learned about his firing from television, which made him look sympathetic and the president’s staff ­incompetent or mean.

Then there’s Trump himself, who keeps adding fuel to the bonfire. His comment to NBC that he had decided to fire Comey before Attorney General Jeff Sessions and his deputy, Rod Rosenstein, had recommended it contradicted the official explanation of the chronology.

The press office and Vice President Mike Pence cited the Sessions-Rosenstein recommendation to explain the decision. In fact, Trump’s letter to Comey cited it, too, saying, “I have accepted their recommendation and you are hereby terminated and removed from office, effective immediately.”

Suddenly, that was no longer true, delivering a blow to the ­administration’s credibility.

Then Friday, Trump upped the ante by warning darkly about “tapes” in a tweet that cautioned Comey not to leak . A president igniting speculation about secret Oval Office recordings is like a shipbuilder musing about the ­Titanic. No, no, no.

Meanwhile, in more evidence that Comey was canned in haste, the search for a replacement is at the starting gate, with Fox News saying there are 11 possible ­replacements.

So why the rush to create a ­vacancy if there wasn’t a ready upgrade, especially when the acting director, Andrew McCabe, brings his own political baggage? With background checks and confirmation hearings, he could be in the job for months.

I recognize it’s still early days for the administration, and that Trump’s talent for disruption is a big part of his appeal. I also recognize that his campaign often veered off-road and he still pulled off one of the great political ­upsets in American history.

But a presidency, for all its power and grandeur, is fragile. Its strength comes from the consent of the governed and the mandate to lead must be constantly earned and expanded. Nothing is guaranteed.

Trump may thrive in chaos, but his staff, the government and the public require more order and certainty. Because he inherited plenty of crises, there’s no need to create new ones.

So here’s my plea, Mr. President: Make it easier for others to keep the faith. You’ll accomplish much more and many more Americans will be proud to stand with you.

Poisoned Ivies

Headline: “Dartmouth Announces Linda Sarsour Lecture, Days After Refusing to Co-Sponsor Event Featuring Israeli Soldier.”

One campus at a time, it’s all downhill in the mad house formerly known as the Ivy League.

He’s out on bad behavior

The resignation of the city’s embattled correction commissioner ended one of the strangest sagas in the strange tenure of Mayor de Blasio.

Joseph Ponte quietly called it quits Friday afternoon, with City Hall releasing statements from him and the mayor. Ponte said he was retiring and de Blasio praised him for pretty much everything except sliced bread.

Never mind that Ponte was hounded out of town because investigators discovered he improperly used his city SUV for 18,000 miles in out-of-state travel, mostly to Maine, where he had worked and lived. His travels included 35 days when he claimed to be working, which might help explain why violence at Rikers Island keeps climbing.

Yet the really bizarre behavior belongs to de Blasio, who relentlessly defended Ponte despite the misuse of the SUV and other issues that normally bring punishment. The mayor wouldn’t have it, offering a variety of excuses, none of which passed the smell test.

The mayor also insisted Ponte made the jails safer when City Hall’s own stats say they’ve gotten more violent.

The mayor, of course, wasn’t really defending Ponte as much as defending himself. Up for

re-election, he’s trying to hide anything that makes him look bad so he can paint a rosy picture for voters.

There’s nothing novel in that — except that spin ceases to be spin when it involves flat-out lies. Perhaps the mayor is so involved in the political game that he’s forgotten the difference. If he ever knew it.

Rent coming due for Crowley

It looks as if something shady is brewing with Queens Congressman Joe Crowley. The Post reports that Crowley, the fourth-highest-ranking Democrat in the House, used campaign money to pay $69,700 to rent an office from a company controlled by his brother. Worse, the Elmhurst office is outside his district.

No wonder Crowley hid behind security, then sped off to duck a reporter. He should know he can run but can’t hide.