A year ago, Mayor Rahm Emanuel was fending off calls for his resignation.

Now he’s sending a message: Anyone who wants to take him down is going to have to contend with a lot of dough and the attacks it can buy.

Though the next mayoral election isn’t scheduled until February 2019, two political funds controlled by Emanuel have taken in more than $1.6 million since the start of 2016, according to state campaign records. About $1 million of that money was collected after the beginning of September.

Most of Emanuel’s top donors were unions and wealthy donors who’ve given him big money in the past, records show.

Pete Giangreco, a spokesman for Emanuel’s political campaigns, didn’t respond to questions about the mayor’s re-election plans. He said the donations are the result of the mayor’s work to revitalize the city.

“The mayor enjoys support from both business and labor, in part because he has brought dozens of firms to Chicago and thousands of jobs,” Giangreco wrote in an email. “If labor unions don’t represent working Chicagoans, who does?”

But Ald. Scott Waguespack (32nd), chairman of the City Council’s Progressive Caucus, said the mayor’s fundraising should be seen as a warning shot to potential challengers. “It indicates he can still rake in the cash no matter what his failings have been,” Waguespack said.

Emanuel has a “narrow bandwidth” of wealthy supporters who don’t represent the vast majority of Chicagoans, Waguespack said. “It’s a small number of people who are keeping him afloat.”

The mayor controls two campaign funds: Chicago for Rahm Emanuel and The Chicago Committee. Allies also run a super PAC, Chicago Forward, that can’t officially coordinate with the campaigns. While the super PAC hasn’t raised any money this year, both committees have been active.

Two labor groups — the Chicagoland Operators Joint Labor-Management PAC and the International Union of Operating Engineers Local 399 Political Education Fund — both gave $53,900, the maximum allowed, to each of the committees.

“We were supportive of Rahm Emanuel because of his vision for Chicago, recognizing workers as a vital part of our city,” said Ed Maher, spokesman for the International Union of Operating Engineers Local 150. The union represents 23,000 members, primarily employed in the construction industry in northern Illinois, northern Indiana and southeast Iowa.

Maher said the union also supports Emanuel’s efforts to stabilize the retirement systems for city employees. “He understands that we have more success when we work together.”

Emanuel’s top individual donors over the last year were Michael Sacks, chairman and CEO of the investment firm GCM Grosvenor, and his wife, Cari, who gave a total of $32,400 to his committees. The couple have been leading backers of Emanuel since he first ran for mayor in 2011. Michael Sacks is one of Emanuel’s top advisers and serves as vice chairman of World Business Chicago, a city economic development agency led by the mayor.

In addition to the Sacks’ contributions, other Grosvenor executives donated a total of $14,400. They included Sean Conroy, the son-in-law of former Mayor Richard M. Daley, and Matt Hynes, a former top aide and lobbyist for the mayor.

Michael Sacks did not respond to a call for comment.

Other top donors included:

  • Joel and David Carlins, executives at Magellan Development Group, and their wives, Susan and Rebecca, gave $21,600 total. An additional $12,900 came from other Magellan employees. The firm is building a high-rise condominium and hotel tower near Wacker and Lake Shore Drive.
  • Samuel Mencoff, co-chief executive officer at the investment firm Madison Dearborn Partners, contributed $5,400, as did his wife, Ann. Other members of the firm gave $21,600.
  • Executives at power giant Exelon donated $39,400 to Emanuel’s committees this year. The company’s political action committee chipped in $1,500. “Like other industry leaders, Exelon executives have occasionally supported policymakers from both parties who support sound energy and economic policies,” Paul Adams, a company spokesman, wrote in an email.
  • Employees of C3 Presents, promoters of the Lollapalooza music festival in Grant Park, gave $14,700 to the mayor’s committees.

The mayor’s political standing nosedived at the end of 2015 after the court-ordered release of the video showing Laquan McDonald shot 16 times by police officer Jason Van Dyke. Choruses of critics called on Emanuel to step down. He refused.

Several elected officials have positioned themselves as possible mayoral candidates in 2019, and at least one — Cook County Sheriff Tom Dart — has said publicly that he’s thinking about it. “When he makes a decision either way, he’s going to make it for himself and his family, regardless of what others are doing,” said Ben Breit, an adviser to Dart.

The funds had a total of about $744,000 available at the end of September, when they last filed full reports with the state — and before the latest round of cash came in.