Anthony Weiner is having such a hard time generating support for his limp campaign that he has resorted to paying a rent-a-crowd firm to provide “supporters” for his events, The Post has learned.

Some of the gung-ho Weiner crowds, including at the Aug. 11 Dominican Day Parade in Manhattan, were really actors who were paid $15 an hour by the California firm Crowds on Demand, according to a source with direct knowledge of the deal.

The source said surrogates for Weiner approached the Santa Monica-based company days after Indiana-native Sydney Leathers came forward to say that Weiner had continued his digital dalliances after resigning from Congress.

The campaign asked the company to have actors seem “like either supporters or people who met him and became supporters as a result of that encounter,” the source said.

“The people would initially be skeptical and then they ask him various questions but would appear then to be convinced by his spiel,” according to the source, who said the campaign used Crowds on Demand “several times.”

Initially, Weiner’s associates asked the company to try and confront hecklers, but the company — fearing liability if there was violence — refused, the source said.

Crowds on Demand had no comment.

Weiner’s camp denied employing the company.

“We’ve never heard of this company and certainly never used them,” said spokeswoman Barbara Morgan. “We are proud we’ve always had the biggest and most fired-up crowds. That’s enthusiasm the other campaigns just can’t buy.”

Soon after that statement, the campaign released a new commercial using interns to pose as regular New Yorkers who support the long-shot candidate.

In a 30-second ad, 18-year-old Joel Acevedo from Staten Island looks at the camera and proclaims, “As an 18-year-old, first time voting, I decided to vote for the future of New York.” He never mentions he is an unpaid campaign volunteer, but lists Weiner for Mayor as an employer on LinkedIn.

Another person featured in the ad, Mary Elizabeth Elkordy of Queens, used to work as a fund-raising intern for Weiner’s congressional office from December 2008 to June 2009.

“Unlike our opponents, we don’t rely on open casting calls for folks in our ads,” Morgan insisted. “Our campaign is constantly recruiting supporters to help out. Perhaps that’s why we have so many.”

Apparently, Weiner can’t get enough of interns — or hold on to them. His campaign sent out a solicitation yesterday for more interns and volunteers even though there are only two weeks left until the Sept. 10 primary.

The ad says Weiner is looking for highly motivated, organized, and energetic people to join the “most exciting campaign of the year.”