Republican presidential candidate Donald Trump purchased this 128-room Palm Beach mansion in 1985 for a bargain price and turned it into a private club. But the mansion has brought Trump some controversy in the sunny Florida city. (Rosalind S. Helderman, Mary Jordan and Victoria M. Walker/The Washington Post)

In the last month — since President Trump said there were “fine people” among those marching in a violence-plagued “Unite the Right” demonstration in Charlottesville — the president’s Mar-a-Lago Club in Florida has been deserted by 19 charities that planned to use its ballrooms for fundraisers.

This week, another group decided it should be number 20.

Those charities are key customers of Trump’s club: They can pay as much as $275,000 for a single night’s revelry. They also are an important marker of prestige in Palm Beach: When big galas are going on in Mar-a-Lago’s ballrooms, the island’s elite must come to Trump, gathering at a club that doubles as his home. Even as president, Trump has reveled in this role: He has dropped in to glad-hand and address the crowds.

Now, this exodus of customers has highlighted an unexpected consequence of the president’s decision to keep ownership of his businesses while in the White House.

That decision has made Trump money, certainly. It allowed businesses and governments seeking the president's favor to funnel him money through his D.C. hotel. But it has also driven away customers, by injecting Trump’s divisive brand of politics into every business transaction — even a decision to rent a ballroom 990 miles south of Washington.

The charities deserting Mar-a-Lago have been the most visible sign that President Trump's divisive brand of politics have driven away some of his business's longtime customers. But there are other examples: The Washington Post recently found that dozens of prior clients have left Trump properties across the country since he entered the 2016 presidential race. At least 30 have been explicit that they are leaving because of Trump's political career.

As for Mar-a-Lago in particular, here are four questions and answers about what’s happened so far.

How many charities have canceled in the last month?

In all, 20.

That includes 12 charities that had planned galas or other large dinner events. These are the most important events of Palm Beach’s traditional winter “season,” when wealthy people from colder climes gather for five months of gala balls, golf, croquet lessons, sequins and pastel fabrics. Some of the biggest charity galas can attract 600 people or more and raise more than $1.5 million in an evening.

In addition, seven charities have cancelled or moved luncheon events they had planned at Mar-a-Lago. These events bring in less money for the president's club, but the sums are still large: $50,000 or more per event. A 20th group, the Palm Beach Symphony, announced it would move its event to a rival club this week.

One of the latest charities to leave Mar-a-Lago was the Palm Beach Habilitation Center, which had held its "Hab-a-Hearts" luncheon at Mar-a-Lago for at least nine years running. In past years, that charity had reported spending about $70,000 a year on expenses related to the luncheon, although it did not specifically list how much of that money went to Trump's club.

The charity announced in early September that it would move the next event to another site.

“We’ve decided to move because we want to keep the focus of the event on our mission, which is to help adults with physical or mental challenges live the best lives possible," Habilitation Center CEO David Lin told the Palm Beach Daily News.

Even before this exodus of clients, Mar-a-Lago was facing an unusually slow season. It had only 16 galas on the schedule for the winter, compared with 21 the year before and 26 in its best year.

But the new departures have decimated its remaining business. As of now, just four galas and two other events -- a brunch and a lecture -- remain on the schedule. If no more events come in, that would make this the slowest season for special events at Mar-a-Lago in at least 10 years.

The groups canceling galas or dinner events have included the American Red Cross, the Salvation Army, the American Cancer Society, American Friends of Magen David Adom, Leaders in Furthering Education, the Palm Beach Zoo, the Preservation Foundation of Palm Beach, the Susan G. Komen breast cancer charity and the Autism Project of Palm Beach County.

In addition to the Palm Beach Habilitation Center, the charities that have canceled luncheon events at Mar-a-Lago were the Ryan Licht Sang Bipolar Foundation, MorseLife, Hearing the Ovarian Cancer Whisper, the Unicorn Children's Foundation and Big Dog Ranch Rescue.

Most of these groups said they would move their events to other venues. The Unicorn Children's Foundation said it would cancel its event outright, missing out on what the charity expected would be $160,000 in donations from the event. In most other cases, the charities have indicated they will seek another venue for their events, instead of canceling them entirely.

Which nonprofits are sticking with Mar-a-Lago?

So far, we know of five -- and another charity that has moved to Mar-a-Lago, even as others moved away.

The Palm Beach Police Foundation — whose Policeman’s Ball is one of Mar-a-Lago’s largest events — is “continuing with its plans” to hold the gala there again in 2017, spokeswoman Maureen O’Sullivan said.

The same is true for the Palm Beach County Republican Party, which has held its annual Lincoln Day dinner at Mar-a-Lago since 2013. “We have no plans to switch venues,” the party's chairman, Michael Barnett, wrote Sunday.

The good news for Trump’s club is that these two events are among Mar-a-Lago’s highest-paying event customers. The police foundation paid $276,000 to Trump’s club for rent, food and beverages at one recent gala, according to tax records. The Palm Beach County Republican Party pays about $145,000 for its dinner, Barnett said.

Other staying include the Cavallino Classic, an annual car show that hosts a Sunday brunch for charity on the expansive lawn at Mar-a-Lago in January. The event's organizers say it's almost impossible to find such a large expanse of open area in Palm Beach itself.

In addition, a new event called the "Truth about Israel Gala" has been added to Mar-a-Lago's schedule, taking a date that another charity had abandoned. That event's organizer, Steven M. Alembik, said he wanted to use the event as a way of thanking President Trump for Trump's policies toward Israel. “He’s got Israel’s back,” Alembik said. “We’ve got his back." He estimated that the event might raise $420,000, and that Trump's club would end up with most of it.

The coastal Trump National Golf Course Los Angeles used to be a sought-after spot for golfers, weddings, celebrities and film crews alike. But after President Trump's campaign announcement in 2015, permit requests, tournaments and fees all shrank. (Jenny Starrs/The Washington Post)

Are more cancellations coming?

That seems possible.

On Monday, a group called Achilles International — whose Achilles Freedom Team helps wounded veterans — met to decide whether to cancel or move its planned "Spirit of America Holiday Dinner" set for this winter at Mar-a-Lago.  There were definite hints of tension: Mark Weiss, the co-chair of Achilles International, told The Post recently, "While Donald Trump has, in the past, been personally philanthropic with our organization, we are horrified by his recent comments. As well, we especially hated his disparagement of people with disabilities during the campaign."

But the group — which has held similar dinners for the last two years at Mar-a-Lago, where one of the group's leaders, Mary Bryant McCourt, is a member — ultimately decided to "move forward with the event" at the club. Weiss told The Post in a statement Monday, "We will not allow undue social media pressure by political activists to keep us from our mission."

Other groups recently have made a different choice. On Thursday, the Palm Beach Symphony announced it would move its February concert from Mar-a-Lago to The Breakers, a competing club nearby. But the group's director told the Palm Beach Daily News that the move was because of scheduling conflicts with other classical-music events — not the president's politics.

How much is this costing the president?

It’s hard to say for certain.

Officials at the Trump Organization did not respond to a question about how much revenue Mar-a-Lago will lose because of the canceled events. Many charities won’t reveal how much they paid. It’s also unclear whether the charities that already had paid deposits are getting that money back.

The big gala events each seem to bring in more than $100,000 per night, according to a survey of charity leaders and tax documents. The luncheons can bring in anywhere from $24,000 to more than $80,000.

Even these lowball numbers yield an estimate of $1.1 million in revenue that Trump’s club could have expected from the 18 lost events. That’s a significant sum, although Mar-a-Lago has other streams of revenue: initiation fees, member dues, hotel suites and restaurants and bars catering to members and guests.

In recent years, Mar-a-Lago has run profits between $4 million and $8 million, according to documents the club filed in court in Florida.

What has the president said about all of this on Twitter?

So far, nothing at all.