An old story from Albany is unforgettable. Gov. Nelson Rockefeller was a skilled arm-twister, but one legislator, a fellow Republican, resisted demands to vote a certain way, even rejecting offers of pork-barrel spending in his district.

Feeling triumphant, the legislator looked at Rocky and declared, “There’s nothing you can give me I don’t have.”

“Yes there is,” the governor ­responded cooly. “A primary opponent.”

With that threat, so the story goes, Rocky got his man.

The anecdote has always been a favorite for what it says about power and how successful pols use it. Rockefeller, like Lyndon Johnson, believed every legislator had a price — he just had to find it.

Which brings us to President Trump, and his growing problems with congressional Republicans. Too many are bucking him, making it hard to get big things done.

Even before the collapse of ObamaCare repeal, the president felt abandoned by his party because few had risen to defend him from special counsel Robert Mueller. “It’s very sad that Republicans, even some that were carried over the line on my back, do very little to protect their President,” he tweeted, a theme one of his sons elaborated on Monday.

“I want somebody to start fighting for him,” Eric Trump told Sean Hannity on Fox News. “My father has the voice of this country. The people of this country love him. Why wouldn’t they [Republicans] get in line?”

He added, “It doesn’t make sense.”

Actually, it does make sense — political sense, which should never be confused with common sense or any other sense.

Political sense is about personal survival, and Republicans are pulling away from Trump because they see it as safer than getting too close to him. And neither his complaints about them nor his threats to end their ObamaCare subsidies is likely to change their calculations.

Simply put, Donald Trump’s power is seen as weak in Washington. He’s not loved, and he is not popular enough to be feared.

Trump has the Oval Office and the bully pulpit, but official power isn’t always the same as political power. Unlike Rockefeller, Trump is in no position to back a primary opponent against incumbent ­Republicans who oppose him.

He doesn’t have an outside political operation — witness the fact that no Trump super PAC or any other group ran a single ad promoting the repeal of ObamaCare. There is no nominally independent organization to push his agenda, such as the one President Barack Obama had.

“Organizing for America” was an extension of Obama’s campaign and was run by campaign aides to keep his voters engaged and in support of his agenda.

Trump never had much of a campaign structure, and the lack of outside support now deprives him of an enforcement mechanism. One result is that most Democrats, despite what happened last year, increasingly believe that ­resisting Trump is the best path to success.

Trump’s predicament is why the appointment of Gen. John Kelly as chief of staff is so critical. It can be a turning point — if Kelly can stop the damaging leaks and bring a sense of order to the White House.

In that case, skeptical GOP lawmakers would be more inclined to stick closer to Trump. They might even be able to wake up each morning without fearing a new Twitter storm.

Trump’s poll results illustrate his power and its limits. As David ­Byler notes on Real Clear Politics, despite a “roller coaster of events,” Trump’s job approval has stayed stable at about 40 percent for more than two months.

That fact, he says, has pollsters debating the whys and offering various theories, including partisan polarization and the possibility that 40 percent is Trump’s floor.

Yet a number within the numbers is revealing. On economic ­issues, Byler reports the average of recent polls gives Trump a 44.7 percent approval rating, close to the 46 percent of the popular vote he won last year.

That strikes me as the obvious path forward for Trump. His White House reset must focus relentlessly on the very issues that got him elected — his America First agenda, especially jobs, jobs, jobs.

In fairness, the problem isn’t that the president hasn’t talked about that agenda enough. He often does, boasting about stock-market record highs, falling unemployment and increased confidence. His executive orders and regulation cuts amount to low-hanging fruit that are giving businesses a boost.

The problem is that Trump too often steps on his own good news, and feeds the media beast the scandal and chaos news it wants. That dynamic is putting a ceiling on his popularity that is close to his floor.

To move Republicans, Trump has to first get out of his own way. His political power in Washington will grow with his job-approval numbers around the country.

And if he really keeps himself on the straight and narrow, Trump might be able to peel off a few Democrats who fear his popularity in their states. That was Trump’s plan when he took office, so getting it done would be a very big deal.

NY can’t ‘bare’ police inaction

On its surface, failure by the police to enforce restrictions on solicitations by painted women and cartoon characters in Times Square is a nuisance. Tourists get hassled, but, so far, nobody gets hurt.

But beneath the surface, the inaction is another worrisome sign about the erosion of the city’s quality of life. All the more so because having cops posted to a troublesome area, then not letting them enforce the law, recalls some of the worst of the bad old days.

Back then, beat cops were derided as “blue flowerpots” because many were not allowed to make street arrests, even when they saw crimes being committed. That was especially true of drug crimes, with police brass worried that young cops would be tempted by bribes. So they ordered them to do nothing.

That was hardly a solution, and the city got worse and worse until cops were allowed — and expected — to be cops. That meant enforcing the law.

Yet here we go again, with that essential idea being looked upon as quaint. Apparently, New York will decline until a future occupant of City Hall rediscovers the lesson that not enforcing some laws only breeds contempt for all laws.

Big drip Comey ‘keeps leaking’

Jim Comey is still leaking.

That’s the only conclusion to draw from a story published by The New York Times and others that shortly after President Trump fired Comey as FBI director, Gen. John Kelly, then head of Homeland Security, called Comey to say he was so upset, he was thinking of quitting in protest.

That the story, citing anonymous sources, appeared on the day Kelly became Trump’s chief of staff shows Comey trying to undermine the president, even if it means people like Kelly are collateral damage. His dirty conduct shows he remains “J. Edgar Comey.”

Well, it’s about time.