WASHINGTON (CNN) A campaign-finance watchdog group filed a complaint Wednesday, urging federal regulators to investigate the fundraising tactics of New York Mayor Bill de Blasio's presidential campaign and two political action committees tied to him.

In its complaint to the Federal Election Commission, the Campaign Legal Center alleges that de Blasio and his campaign "concocted a shell game" that allowed wealthy donors to make excessive contributions to the mayor's 2020 presidential campaign by contributing to his political action committees, Fairness PAC and NY Fairness PAC.

The complaint also alleges de Blasio's campaign violated federal reporting requirements by not disclosing those contributions on its FEC filings and not divulging all of the spending made by the political action committees to advance de Blasio's presidential ambitions.

Individuals cannot donate more than $2,800 to a 2020 presidential candidate for the primary election. The Campaign Legal Center said at least 25 donors who contributed the legal maximum to de Blasio's campaign also gave another $5,000 to the de Blasio PACs this year as he began exploring a presidential bid.

"By setting up this scheme, de Blasio allowed a small handful of wealthy donors to give thousands of dollars above the legal limits, which are designed to prevent corruption and undue influence," Brendan Fischer of the Campaign Legal Center told CNN.

"We are reviewing the complaint," de Blasio campaign spokeswoman Olivia Lapeyrolerie told CNN on Wednesday. In the past, de Blasio aides have argued that the mayor's use of the PACs -- initially promoted as a tool to help liberal Democrats win national and state seats -- does not violate the law.

The New York mayor, one of two dozen candidates seeking his party's White House nomination, trails his Democratic rivals in polls and fundraising.

His PACs, which are governed by different rules than presidential committees, paid for hundreds of thousands of dollars in staff, polling and travel as de Blasio weighed entering the presidential race, according to the Campaign Legal Center.

Candidates usually establish exploratory committees to fund their expenses as they test the waters of a presidential bid. Those committees are incorporated into presidential campaigns once candidates formally enter the race. Doing so provides a clear accounting of how the money was raised and spent in the run-up to a White House bid.

Judith Ingram, the FEC's spokewoman, declined to comment on the complaint against de Blasio, citing the agency's longstanding policy of not discussing "pending or potential enforcement matters."

It's not clear that any FEC action would come before the Democratic nomination battle is over. Agency records show that it takes about 14 months, on average, for the commission to resolve complaints.