Donald Trump's presidential campaign announcement last month was widely mocked, not only for the rambling diatribe he used to launch the campaign but for the actors he paid $50 apiece to cheer for it. Journalists responded with a predictable amount of schadenfreude when it was revealed that the Trump campaign hired actors to attend his rally, lighting up Twitter with jokes at Trump’s expense and “You’re Hired!” headlines. The incident was even memorialized with its own coy shout-out by The Simpsons.

Such claims of “astroturfing,” the practice of using money and outside support to create the illusion of grassroots enthusiasm, are not unheard of in the political sphere. The Tea Party movement faced astroturfing accusations from left-leaning opponents during its early years, as did George W. Bush for letters of support sent to a newspaper editor via his website.

The idea of paying for the appearance of excitement offends the belief that a political campaign’s fortunes should be somewhat rooted in genuine support for a candidate. The kind of grassroots fervor generated by Barack Obama in 2008, Ron Paul in 2012, or Bernie Sanders today is aspirational for campaign organizers. But, for politicians with a dearth of excitement, the reason for faking it is obvious: Phony support can generate buzz and media coverage of their campaign—which in turn could theoretically morph into real support, as voters start to hear more about the candidate.

This tactic hasn’t been limited to bids for higher office. Political protests have also used such services to fortify its crowds: The New York Times reported that, during this year’s NYC Pride Parade, a group of anti-gay marriage “protesters” were actually several hired day laborers. Local carpenters unions—notably the Mid-Atlantic Regional Council of Carpenters—have been using such tactics for years, paying temporary workers (and often the homeless) to walk picket lines during a strike.

These days, if a candidate or protest organizer is short on numbers, he or she can simply pick up the phone and call a company like Crowds on Demand, a Los Angeles-based company that provides rental crowds for campaign rallies and protests. The company was founded in late 2012 by Adam Swart, a UCLA grad who majored in political science. It is among a very small number of U.S. companies that offers rental crowd services in the U.S. (including Crowds for Rent and the Trump-hired Extra Mile Casting), and perhaps the only one that does so openly.

While Crowds on Demand was initially geared toward corporate events and PR stunts, Swart says that soon after the company’s founding, would-be elected officials began reaching out for his services in order to give their campaigns a boost. Some have used his services to protest opposing candidates; others have used them to create the appearance of larger turnouts at their own events.

“Our business is about cultivating perception. It’s basic marketing,” Swart said.

Outside of the realm of politics, Crowds on Demand offers an array of crowd-providing services, ranging from a “celebrity shopping experience”—the client mobbed by fake paparazzi outside a posh L.A. boutique—to big PR stunts, such as a 100-person flash mob at a corporate trade show. Swart says his gigs have ranged from two people to hundreds, and that with enough notice (and money) Crowds on Demand can offer more than 1,000 people. But whether the setting is a campaign rally or a convention hall, Crowds on Demand’s goal is always the same: getting people’s attention.

Crowds on Demand offers its services in San Francisco, New York City, and Washington D.C. Thousands of people have applied to be extras with Crowds on Demand. Swart says that he has the most “crowd actors” in cities where real actors tend to try to make it—New York and L.A.—but he has actors available in political hotspots such as Iowa and New Hampshire as well. And while his company generally works in more populous areas, it isn’t limited by geography—or ideology for that matter.

“We’re not a Republican or Democratic group, so we’ll work with both. And third parties,” Swart said, adding that Crowds on Demand’s one major prohibition is against working with hate groups.

While Swart declined to discuss which candidates Crowds on Demand has worked for, the company’s fingerprints have occasionally been spotted. Campaign-finance filings in California show that Crowds on Demand was paid more than $50,000 by the “Six Californias” campaign, a failed ballot initiative funded by Silicon Valley venture capitalist Tim Draper to split the Golden State into six independent states. The New York Post also found that scandalized former congressman Anthony Weiner paid Crowds on Demand actors $15 per hour to turn out for events during his bid for mayor of New York City in 2013.

Similar “crowds-for-hire” companies have also sprung up internationally to create fake support for politicians, including a British company named Envisage Promotions and an Ukranian outfit named “Easy Work,” which paid student protestors $4 an hour to support (and oppose) various politicians. To political experts, these developments are another symptom of a decades-long trend of political professionalization, with campaigns farming out work formerly done by volunteers to a class of paid consultants and specialists. In the case of crowd hiring, it’s actors.

Costas Panagopoulos, director of the Center for Electoral Politics and Democracy at Fordham University, said that he first heard rumblings of the crowds-for-hire idea around the 2010 midterm elections, and is unsurprised that businesses like Swart’s have come to exist. Campaigns already pay for signature gatherers, canvassers, pollsters, direct-mailing services, and extras in feel-good political ads—why wouldn’t they pay to fill a hotel ballroom?

“It’s really another example of just how orchestrated political campaigns are these days, and the degree of attention that’s paid to every dimension. Especially visual elements, like crowd size,” Panagopoulos said.

Though highly-organized and paid-for synthetic support for a candidate may be a fairly new development in American politics, offering a little quid-pro-quo to boost turnout at a political rally is really far from new. “In the 19th century, campaigns did all kinds of things to get people to show up,” said Joe Cummins, the author of Anything for a Vote, which documents seedy campaign tactics used by U.S. presidential candidates throughout history. “If you were an immigrant in those days, the only social safety net was the local precinct of a political organization. Showing up to a rally might mean getting a job, or a meal, or even some money.”

Offering to feed campaign volunteers is generally accepted in American politics; paying them to show up and cheer is up for debate. There might be some gray area between offering a small token of appreciation to otherwise voluntary supporters and full-blown astroturfing, but spending hundreds or even thousands of dollars to prop up a struggling cause seems to fit more squarely in the latter category.

For his part, Mr. Swart is adamant that what Crowds on Demand and companies like it do is ethical—and says it’s more ethical than many other modern campaign tactics. “I say it’s far less misleading than negative TV ads that are often proven to be half-truths or complete fabrications,” Swart said. “I’m engaging with the political process and making people think.”

Still, even Swart admits that a revelation that a campaign is paying for supporters is deeply embarrassing, and he takes great pains to keep his clients’ identities a secret. And for his purposes, probably rightly so. The Trump episode illustrates that the public—and certainly the media—still prefers that crowds be assembled the old fashioned way: flyers, emails, Facebook invitations, and perhaps a harmless slice of campaign-expensed pizza after the party.