O’Hare Airport employees and the union seeking to represent them plan to demonstrate outside Garry McCarthy’s Sunday fundraiser to question the fired Chicago Police superintendent’s motivations for running for mayor.

Jerry Morrison, assistant to the president of SEIU Local 1, charged that McCarthy’s threat to challenge Rahm Emanuel is little more than a “crass attempt” to bully the mayor into renewing a five-year, $107 million O’Hare janitorial contract with United Maintenance.

The company is owned by Rick Simon, McCarthy’s friend and former business associate. SEIU Local 1 is part of a group of unions that now owns the Chicago Sun-Times.

“Garry McCarthy has a hundred million reasons to say that he’s running for mayor – and that’s the $100 million cleaning contract at O’Hare. It’s a fairly crass political play. I don’t know that he’ll directly make that kind of ask. But it’s implied that, ‘I will get out if you renew my buddy’s contract,’ ” Morrison said Friday.

“That’s what has Rick Simon and [Ald.] Ed Burke very, very concerned….They have feverishly worked City Hall, including Ed Burke forcing aldermen to meet with Rick Simon to talk about how this contract gets renewed.”

Two years ago, United Maintenance shelled out nearly $850,000 to settle a federal wage-theft lawsuit brought by its O’Hare employees.

“Richie Simon…has a terrible track record out there — stealing millions of dollars of wages from the workers and running a non-union shop. I think that’s what McCarthy’s alleged mayoral run is all about,” Morrison said.

Simon and Burke, chairman of the City Council’s Finance Committee, could not be reached for comment. Shortly after McCarthy was fired, the former superintendent opened a security consulting business in a Simon-owned South Loop building that also serves as the headquarters for United Maintenance.

McCarthy said he could care less about the protest outside his $100-a-ticket fundraiser, scheduled for 12:30 p.m. Sunday at the Irish American Heritage Center, 4626 N. Knox.

“The whole thing is nonsense. It’s completely made up. I’m not gonna talk about it….I’m not gonna play this stupid Chicago game,” he said.

Asked about Morrison’s claim that McCarthy is engaging in a “crass” form of political blackmail to help Simon, McCarthy said, “Sounds like Dan Mihalopoulos’ bull-s—t….I’m not gonna talk about this because it’s bull-s—t. I’m not gonna play into it. Just like Donald Trump. I’m not gonna play into that either.”

Mihalopoulos is a Chicago Sun-Times investigative reporter who first questioned the tie between Simon’s now-expired-and-extended janitorial contract and McCarthy’s decision to consider challenging the mayor who fired him.

Last month, Simon told Mihalopoulos that McCarthy “did some consulting work” for United Maintenance, hasn’t worked for the company in “at least a year” and moved out of the South Loop building a while ago.

The O’Hare janitorial contract has been a source of controversy from the outset.

It was awarded in 2012 over heated union opposition. At the time, the Sun-Times reported that the company had failed to comply with a contract requirement to disclose all of its investors.

Instead of seizing on that infraction and cancelling the contract, as the city was empowered to do, Emanuel let the deal go through, infuriating SEIU Local 1.

Last year, Emanuel made amends by convincing the City Council to approve a groundbreaking ordinance that guarantees nearly 8,000 contract employees at O’Hare and Midway an hourly wage of “no less than $13.45.”

The ordinance ties licenses for airport contractors to a “labor peace agreement” that allows baggage handlers, cabin cleaners, aircraft maintenance workers and security guards to organize and prohibits contractors from interfering or preventing those workers from “engaging in strikes, picketing, work stoppages, boycotts or other economic interference.”

At least one of the leafleting protesters outside McCarthy’s fundraiser plans to wear a Donald Trump costume.

That’s because Trump once called McCarthy a “phenomenal guy” and because McCarthy proudly accepted a $5,600 contribution from his former boss, New York City Mayor Rudolph Giuliani.

“That all tends to indicate that you’re a Republican. Rudy Giuliani doesn’t give $5,600 checks to Democrats,” Morrison said.

“Who did you vote for for president? Did you vote for Hillary [Clinton]? Did you vote for Barack Obama? We need to have some indication that you’re a Democrat. You’re running in a city that’s 80 percent Democrat. Garry McCarthy, tell us if you’re a Democrat or a Republican. Every indication is, you are a Republican.”

McCarthy says he’s “been a Democrat from the day I could vote” and he “shouldn’t have to” explain whether he is for or against Trump — not even in this overwhelmingly Democratic city.

Political funds controlled by Burke have received at least $55,000 in contributions in recent years from Simon’s United Maintenance and United Service Companies, records show.