Former Miami City manager Joe Arriola is raising money to reelect Miami-Dade Mayor Carlos Gimenez, and pitching donors on a nonprofit that will keep their contributions a secret. Gimenez’s main challenger, Raquel Regalado, says she is also referring donors to the same kind of nonprofit if they want don’t want the public to know they’re backing her campaign.

In a recent email to prospective donors titled “We must reelect Mayor Gimenez,” Arriola asked for support of a tax-exempt organization called the Business Action League. “Donors to Business Action League are not publicly disclosed; there are no limits; and both individual and business contributions are permitted,” he wrote.

Arriola’s role attaches a high-profile figure to a group that has operated in the periphery of the 2016 mayoral race as Gimenez tries to fend off a challenge from two-term school board member Regalado and five lesser-known rivals. In an interview, Arriola said he’s raising money to promote a “different view about what the race is all about.”

“I want to talk about the business side” of the mayoral contest, he said.

The Business Action League, which sponsored pro-Gimenez ads last summer, is organized as a 501c4, the kind of nonprofit reserved for influencing public policy. It can run advertising that skirts the line of endorsing candidates (the Business Action League ran newspaper ads last summer “thanking” Gimenez without urging anyone to vote for him), but can’t be involved once a campaign officially begins roughly 90 days before Election Day.

Regalado, the daughter of Miami Mayor Tomás Regalado, also has a 501c4 backing her called the Miami-Dade Partnership for Prosperity, the group’s chairman, Roland Sanchez-Medina, confirmed Monday. Sanchez-Medina also heads the state political committee, Serving Miamians, that is backing Regalado’s challenge to Gimenez. In an interview, Regalado said she will sometimes refer donors to the 501c4 if they are concerned about their support of her becoming public.

“If someone asks me: ‘Hey, listen, I’d like to help but I have an issue. I have business before the county. I say call [Sanchez-Medina],” she said.

In a text message, Sanchez-Medina said the committee was formed as a counter-measure to what he called Gimenez’s “predatory fundraising.” He accused Gimenez of “telling people that contributing to Raquel Regalado puts them and their businesses with Miami-Dade County in peril.”

A Gimenez spokesman, political consultant Jesse Manzano-Plaza, denied Sanchez-Medina’s allegation and cited violations from her role in managing her father’s 2009 mayoral campaign. “We hold ourselves to higher standards and do not resort to those types of practices,” said Manzano-Plaza. “We have a campaign and a political committee, and we are raising funds for those. The information on who donates to that campaign and that committee are made public every 30 days.” Manzano-Plaza said Gimenez and his campaign was not coordinating with the Business Action League. “We’re not involved with them at all,” he said.

Both 501c4s are registered as Florida corporations. Miami-Dade Partnership for Prosperity lists Sanchez-Medina as the leading officer, while the Business Action League lists as the top director Jim Murphy, a Washington-based political consultant who worked for the Mitt Romney campaign in 2012. Murphy could not be reached Monday for comment.

Gimenez is already dominating the fundraising battle for the 2016 race, with about $2.7 million to spend from his campaign and the political committee he’s raising money for, Miami-Dade Residents First. Regalado’s campaign and Serving Miamians has about $325,000 to spend, according to the latest reports. While those entities file public reports every month, a 501c4 is only required to disclose broad financial activity in its annual tax returns, which become public documents.

Arriola was city manager in 2004 when the city approved a settlement over an ill-conceived “fire fee” case that wound up excluding most taxpayers from a refund in favor of a $7 million payout to seven plaintiffs and their lawyers. The deal was overturned in a series of court decisions, and Arriola said he was misled by plaintiff lawyers into thinking the money would go citywide.

He left the city in 2006, and Arriola now serves as chairman of the county’s Public Health Trust, which oversees the county-funded Jackson hospital system. He also is a director of Perry Ellis, the Doral-based clothing retailer.

Arriola helped Perry Ellis in its pursuit of a no-bid retail lease at Miami International Airport last year, MIA director Emilio González said Monday. González said he met with Arriola and George Feldenkreis, then the CEO of Perry Ellis, at the airport as the company was looking for space last year. “We spoke a couple of times. He visited maybe once or twice,” González said of Arriola. “That’s about it. This was strictly a business deal.”

Perry Ellis and a Cuban restaurant owned by Emilio and Gloria Estefan secured no-bid leases from MIA under an airport initiative targeting local brands. The no-bid agreements later came under fire from black county commissioners questioning why black-owned businesses in Miami didn’t get similar treatment.

J.C. Planas, a Miami-based lawyer specializing in election law, said a 501c4 can keep donations secret while state law requires political committees to disclose donors. But the political committee has the advantage of being able to advocate directly for a candidate, making it more useful in the final weeks of a campaign when a 501c4 must go silent about anyone on a ballot.

“I don’t have many clients that use the 501c4s,” said Planas, who teaches election law at St. Thomas University School of Law. “Yes, some people like the anonymity.”

In the April 10 email obtained by the Miami Herald, Arriola forwards an email from him sent March 9 and tells the recipients to “expect my call regarding this subject.” The March 9 message said he has decided to “head up an effort to help ensure Miami-Dade County continues to benefit from the pro-growth, pro-business policies that are being advocated by Mayor Gimenez.”

In his interview, Arriola said the Business Action League will not disclose donors. “A lot of business people don’t want their names used,” he said. “They don’t want their names exposed out there.”