What started out last year as a straightforward boycott of Donald Trump and his family’s businesses became a lot more complicated when the New York City developer was elected president of the United States.

It’s one thing to aim an economic attack at candidate Trump. But morphing that challenge into direct political action against the president, his policies and the people who support them takes boycotts to a level not seen before.

“Boycott Trump” was an easy enough position to take in the heat of the fall political race. But is it reasonable — or even possible — to repeat that mantra now that Trump has become the leader of the free world?

That’s not a problem to a growing number of people.

“People want an outlet to voice their concerns immediately,” said Jessica Levinson, a professor of law and a political analyst at Loyola Law School in Los Angeles. “One thing we’ve seen in the past few weeks is a growth in political activism, with people willing to show how they feel by voting with their Visas.”

As a billionaire businessman with holdings in highly visible, consumer-based entities like hotels, golf courses and clothing lines, boycotts can have an effect on Trump they never could have had on a former community organizer like Barack Obama or even a one-time oil man like George W. Bush.

“Boycotts can hurt (Trump), both in the pocketbook, since he hasn’t divested himself of his businesses, and in his ego, which he seems to care about a lot,” Levinson said.

The boycott effort started simply enough in October when Shannon Coulter, a Bay Area marketing professional, spotted some Ivanka Trump merchandise on the Nordstrom website.

Just days before, a tape of Donald Trump making lewd boasts about his hyper-aggressive sexual approaches to women was released publicly and “something really changed for a lot of women,” Coulter said in an interview. “I felt I had a responsibility to do more.

“It’s not enough to not buy Ivanka’s collection. She campaigns for him,” Coulter said in an Oct. 11 tweet. “We should avoid stores that carry it.”

Coulter and some friends put together a roster of Trump’s businesses and stores selling his family’s merchandise and listed them online at #grabyourwallet, a none-too-subtle reference to the president’s crude recorded comment about how he liked to grab women by their genitals.

In the months since, the site has taken off, with hundreds of thousands of references and supporters. And as the site has become more popular, the scope of its boycott has also grown, expanding from just stores promoting the Trump brand to companies and individuals with any type of support for Trump.

Macy’s, Bloomingdale’s and Amazon are on the list because they all sell Trump merchandise. But so are See’s Candies and Trident gum, because they advertise on “Celebrity Apprentice,” where Trump is still listed as executive producer. New Balance shoes and LendingTree are boycott targets because their CEOs raised money for Trump’s presidential campaign, as are Hobby Lobby and NASCAR, whose CEOs endorsed Trump.

Maintaining that list has become almost a full-time job for Coulter, who talks online with other boycotters to decide who goes on the list and, equally important, who gets off after backing away from Trump and his businesses.

That widening boycott bull’s-eye is not a concern for Coulter, who sees it as evidence of the worries people have about Trump and his presidency.

But there’s a worry that while Trump is the logical first target for a wide-ranging political boycott effort, he may not be the last.

“You’re talking about a growing polarization, with an increasing number of people who see the opposing party, whether Democratic or Republican, as a threat to the country,” said Corey Cook, dean of the School of Public Service at Boise State University. “Sure, Democrats didn’t like Ronald Reagan, but it was nothing like this.”

As the boycott pushes beyond the personal economics of Trump and his family into the more directly political world of presidential policies and supporters, the questions become stickier.

There’s nothing new or especially unusual about challenging a president’s agenda for the country. But calls to boycott people who support Trump or his policies is something that hasn’t been seen before, and raises the question of just how wide that net of opposition should spread. Is it just donors or business people?

L.L. Bean, a century-old, family-owned outdoor apparel company, is on Coulter’s boycott list because Linda Bean, a board member and granddaughter of the founder, gave $60,000 to one of Trump’s political action committees.

In a Jan. 8 plea to be removed from the boycott list, Shawn Gorman, the company’s executive chairman, wrote that it was a personal donation by one board member and that family members “hold views and embrace causes across the political spectrum, just as our employees and customers do.”

No dice. L.L. Bean remains on the boycott list.

Then there’s Travis Kalanick, CEO of the ride-hailing company Uber. Kalanick was one of 15 members of Trump’s council of business leaders, the type of high-visibility, no-heavy-lifting position that in administrations past served as little more than a photo op allowing corporate executives to brag to their boards and their stockholders about how much the president admires their leadership.

But that was before Trump. When word got out earlier this year that Kalanick was going to be heading to the White House for a sit-down with the president, tens of thousands of customers deleted their Uber accounts in a boycott effort further sparked by outrage against the company for sending its drivers to New York’s John F. Kennedy International Airport last month during a taxi strike protesting Trump’s travel ban.

Kalanick got the message. He quickly resigned from Trump’s Strategy and Policy Advisory Council and began talking tough about his opposition to the executive order on immigration.

“The gloves are off, and everything is fair play now,” said Steve Callander, a management professor at Stanford’s Graduate School of Business. “Companies are getting dragged into political fights, and people are demanding they take a position.”

For companies that make their profits by serving people on every side of every issue, that’s the last thing they want to do, he added.

“It’s up to the companies to figure out the costs and the benefits,” Callander said. “But it’s a free country, and people can buy or not buy goods from whomever they like.”

Political fights after presidential elections, often loud and nasty, are part of the country’s history. Democrats were unhappy about Bush’s controversial victory in the “long count” election of 2000, and Republican politicians famously vowed to do everything possible to thwart Obama after he was elected in 2008.

But the power of even an implied boycott adds a new economic element to the battleground, spreading it well beyond elected officials.

It’s something different, for example, when Kevin Plank, CEO of the Under Armour athletic clothing company, can say that President Trump is “a real asset” to the country because of his plans for job creation and then be forced to walk back that support after a storm of criticism that included complaints from the Golden State Warriors’ Stephen Curry, the company’s best-known spokesman.

“This country has a history of disagreeing vigorously during a political campaign,” and then working together after the election, said Cook of Boise State. “But the prospect of economic boycotts against any business executive who even looks to cooperate with a new president is something both new and frightening.”

John Wildermuth is a San Francisco Chronicle staff writer. Email: jwildermuth@sfchronicle.com Twitter: @jfwildermuth