ANALYSIS:

Never underestimate the power of a supermarket tabloid rag.

Even if you don't actually buy the magazine, it's always there — staring at you as you wait in line to scan your groceries, following you down the stationery aisle or scattered across desks at the doctor's or hairdresser's.

Few are as notorious as the National Enquirer, one of the most powerful print publications in the United States.

The New York-based weekly tabloid has been in circulation for almost a century, with a noted reputation for running salacious celebrity claims, bending — if not completely obliterating — the facts and trashing the reputations of the rich and famous with casual ease.

In 2006, actress Kate Hudson won a lawsuit against the magazine after it implied she had an eating disorder.

The magazine published a two-page story with the headline: "Goldie tells Kate: Eat Something and she Listens! — Star confronts daughter after photos showing her painfully thin."

Carol Burnett took the tabloid to court in 1981 after it was claimed she had been seen drunk in public at a restaurant. It was a particularly sensitive issue for the actress, whose parents were both alcoholics.

In 2012, the magazine ran a controversial cover of Whitney Houston lying in an open coffin shortly after her death was made public — similar to the stunt it pulled after Elvis Presley's death in 1977.

You get the picture.

But the magazine now sits at the centre of a developing scandal concerning Donald Trump — one that could threaten his future as president of the United States.

THE TABLOID THAT BECAME TRUMP'S BEST FRIEND

Over the past few years, Donald Trump has made a firm friend in the Enquirer.

Throughout the 2016 presidential campaign, the magazine puffed up the then-Republican candidate as nothing less than a saint.

"The Real Donald Trump!" declared one cover page headline, with a beaming photo of the would-be president. The inside story was a positive fluff piece detailing his issues with the Obamas and his previous relationships. Above was a photo of him pictured with his third wife Melania Trump, with a smaller headline: "The Future First Lady?"

By contrast, the magazine tore his Republican rival Ted Cruz to shreds, claiming he had multiple affairs and that his father had links to the assassination of former president John F Kennedy.

Once Mr Cruz was out of the presidential picture, the magazine intensified its focus on Hillary Clinton. There was no mercy.

"HILLARY: 6 MONTHS TO LIVE!" blared one headline, with a photoshopped cover image of Mrs Clinton with sunken eyes, exaggerated facial lines and no makeup.

"Failing health and a deadly thirst for power are driving Hillary Clinton to an early grave, the National Enquirer has learned in a bombshell investigation," the story began. "The desperate and deteriorating 67-year-old won't make it to the White House — because she'll be dead in six months."

"HILARY CAUGHT IN SEX-SCANDAL COVER-UP!" screamed another cover.

A third had the simple headline "CORRUPT!" in big white letters against a red background, with a photo of "Crooked Hillary" above, her arms stretched in a prison-orange shirt.

The Enquirer's coverage is relentless. No story is too over-the-top; the magazine linked Ms Clinton to brain cancer, child prostitution, bribery and treason, seemingly without hesitation.

"It was like a double whammy," Jennifer Palmieri, Mrs Clinton's campaign communications director, told The New York Times. "They could have been covering all of Trump's misdeeds. But, instead, not only were they not reporting on that, they were a pipeline from dark-net conspiracy theories to grocery-store lines."

At the centre of the magazine sits David Pecker, the longtime chief executive of American Media Inc, its parent company.

As the magazine has few subscribers and minimal advertising, it relies on combining certain celebrities and phrases to sell itself. Jennifer Aniston, Brad Pitt and Angelina Jolie, Dolly Parton and the Kennedys are all time-tested winning subjects, as are phrases such as "six months to live" and "sad last days".

But as far as Pecker was concerned, anything remotely negative about Mr Trump was off-limits.

In a 2017 feature piece on the tabloid, The New Yorker described an editorial meeting in which someone suggested a story on the now-infamous video from Mr Trump's first overseas trip with his wife Melania.

The viral video showed Ms Trump swatting her husband's hand away as he attempted to grab it on the red carpet.

"I didn't see that," Pecker said in response to the suggestion.

The men in the room exchanged looks. One noted that there was footage online, which had been seen by millions of people.

"I didn't see that," Pecker repeated, and that was the end of the matter.

The Times noted that Mr Trump's personal life epitomised — by its own branding, at least — the meat and bones of the magazine.

"The Enquirer was built to cover Mr Trump's wild ride," it said. "If it had only stuck with its original mission — digging up dirt on the rich and famous, without a care for the rules of traditional journalism — it would have had the tabloid story of a lifetime," the Times wrote.

So why was Mr Trump let off the hook, and instead the subject of non-stop gushy praise?

According to The New Yorker, Pecker and Mr Trump have been friends for decades. Pecker even attended the billionaire's wedding with Melania in 2003.

The editor openly admitted his tabloid's gushing coverage of Mr Trump had a personal element. But he also said — similar to salacious stories about Jennifer Aniston or the Brangelina dispute — it was ultimately a case of giving the people what they want.

"They voted for Trump," Pecker said. "And 96 per cent want him re-elected today. That's the correlation. These are white working people, who love to see take-downs of celebrities, and they want to see — which is unusual, who would think these people would love a billionaire? — the billionaire's pulpit. They know him from fourteen seasons on The Apprentice as the boss, and they loved it when he fired those people and ridiculed them."

According to a former Enquirer employee, Pecker idolised Mr Trump. "David thought Donald walked on water," the employee told The New Yorker. "Donald treated David like a little puppy. Donald liked being flattered, and David thought Donald was the king. Both have similar management styles, similar attitudes, starting with absolute superiority over anybody else."

They say you can't put a price on friendship, but apparently you can. According to the Times, a campaign with the same level of prominence handed to Mr Trump by the magazine would cost up to $US3 million a month.

But now, a very different story is emerging — one that could shatter Mr Trump's future in the White House.

TABLOID MAG THREATENS TRUMP'S FUTURE

Last week, Enquirer parent company American Media Inc admitted to making a $US150,000 payment "in concert with" Mr Trump to former Playboy model Karen McDougal, who claimed she had an affair with the billionaire in the mid-2000s.

The contract was made in September 2016 — two months before election day — and would have been a hell of a story for the celebrity magazine.

Only it never ran, and the payments were actually part of a "catch-and-kill" operation to keep McDougal quiet.

The revelations came as Mr Trump's former lawyer, Michael Cohen, was sentenced to three years in prison for orchestrating the pay-offs, which amounted to an illegal campaign contribution.

He was also ordered to pay almost $US1.4 million in restitution and forfeit $US500,000, and was fined $US50,000 for lying to Congress.

Prosecutors declared that the company, and Pecker himself, had admitted to the $US150,000 payments in exchange for immunity from prosecution.

In August 2015, Mr Cohen met with Pecker and "at least one other member of the Trump campaign" in Trump Tower.

"At the meeting, Pecker offered to help deal with negative stories about that presidential candidate's relationships with women by, among other things, assisting the campaign in identifying such stories so they could be purchased and their publication avoided," the agreement read. "Pecker agreed to keep Cohen apprised of any such negative stories."

The third member in the meeting? That was Mr Trump himself, The Wall Street Journal first reported last month.

In other words, Mr Trump allegedly sat at the centre of a conspiracy to pay off the company to silence his alleged mistress and enhance his election prospects — an offence that carries jail time.

When Mr Cohen pleaded guilty to arranging the payments, he said he'd done so "at the direction" of an unnamed person.

The statement of admitted facts says the company's "principal purpose in making the payment was to suppress the woman's story … to prevent it from influencing the election".

During his sentencing, Mr Cohen said that "time and time again, I felt it was my duty to cover up (Mr Trump's) dirty deeds".

While the White House declined to issue an official statement, Mr Trump responded on Twitter saying he "never directed Michael Cohen to break the law".