It looks like Mayor Rahm Emanuel is finally starting to shift his legendary fundraising machine into high gear for the difficult re-election campaign ahead.

Emanuel raked in $112,500 in just one day this month — thanks, in large part, to two trade unions and heavyweights in the entertainment industry, where his brother, Hollywood super-agent Ari Emanuel, wields huge influence.

The new wave of contributions includes: $30,400 from the Ironworkers Political Action League and $15,000 from the Bricklayers and Allied Craftworkers PAC. Both unions stand to benefit from the bonanza of jobs and contracts tied to Emanuel’s proposed, $8.5 billon O’Hare Airport expansion project.

The Hollywood star power comes from: HBO writer Larry David of “Curb Your Enthusiasm” and “Seinfeld” fame, a client of Ari Emanuel ($5,000); STARZ executive Chris Albrecht ($5,600); David Pecker, chairman of American Media ($5,600); Cynthia Pett-Dante, co-president of Brillstein Entertainment ($5,600); Michael Lombardo, producer of Film 44 ($5,600); Tom Rothman, chairman of the motion picture group for Sony Pictures Entertainment ($5,000); Nancy Dubac of A&E Networks ($5,000); Jeffrey Ross, executive producer for Conaco ($2,000) and Universal Film Chairman Jeff Shell ($1,000).

In 2015, Emanuel survived Chicago’s first mayoral runoff — but only after spending a record $24 million, four times more than County Commissioner Jesus “Chuy” Garcia, a relative political unknown.

To win a third term, the mayor probably needs to set a new fundraising record. That’s what it likely will take to overcome the deep distrust in the black community caused by violent crime, school closings and Emanuel’s handling of the Laquan McDonald shooting video and the citywide backlash from a $1.2 billion avalanche of tax increases imposed to help solve Chicago’s $36 billion pension crisis.

The mayor closed the books on 2017 with less than $2.1 million in the bank, nowhere near what he would need to fend off possible mayoral challengers Paul Vallas and fired Chicago Police Supt. Garry McCarthy, as well as already-declared candidate Troy LaRaviere, head of the Chicago Principals and Administrators Association.

Last month, a mayoral confidant told the Chicago Sun-Times that Emanuel had been “on a fundraising tear of late” that was likely to be reflected in the next quarterly report. The most recent report filed with the Illinois State Board of Elections is evidence of that fundraising tear.

To raise money quickly in even larger chunks, the mayor would need a friendly union or deep-pockets donor to blow the fundraising caps that currently limit contributions to $5,600 from individuals, $11,100 from corporations, labor organizations and associations and $55,400 from candidate political committees and political action committees.

That’s precisely what happened in 2015, courtesy of William Kelly, who threatened to challenge Emanuel, but never did.

“Once he does everything he needs to do, which he’s in the process of doing, he’ll have plenty of resources — no doubt,” the Emanuel confidant said.

“Just about every major race, the caps have gotten broken. I would not be shocked if that happens in this race again.”

Vallas told reporters last month he intended to enter the 2019 race for mayor, so long as he can raise enough money to get his message out, and introduce himself to voters who don’t remember his widely acclaimed tenure at CPS.

But he has since been hit by a devastating personal tragedy: the death of his youngest son, 24-year-old Mark Vallas.

McCarthy has set up a website, held a fundraiser and commissioned a poll that will help him decide whether he can wage a winnable race against the mayor who fired him. He raised $49,184, spent $47,711 and ended the year with just $1,572 in the bank.

LaRaviere, a former CPS principal, has also launched a fundraising website.

The wave of Hollywood contributions were reported on March 1, but it was not known when the fundraiser was held.

On Feb. 13, the day beloved 18th District Commander Paul Bauer was gunned down outside the Thompson Center, Emanuel was in Los Angeles to speak at UCLA, where his son, Zach, is a student. A handful of demonstrators protesting the mayor’s decision to build a $95 million police and fire training academy disrupted Emanuel’s speech, just as college students have done during other campus visits.

The mayor typically mixes political fundraising with city business on his travels across the country.