A non-profit founded by Mayor Bill de Blasio to advance his political agenda said Friday it will not comply with a subpoena from the New York State Joint Commission on Public Ethics, one of multiple federal and state agencies investigating whether the group violated the law. View Full Caption Demetrius Freeman/Mayoral Photography Office

MIDTOWN — A nonprofit founded by Mayor Bill de Blasio to advance his political agenda said Friday it will not comply with a subpoena from the New York State Joint Commission on Public Ethics, one of multiple federal and state agencies investigating whether the group broke the law.

Laurence Laufer, attorney for the Campaign for One New York, said the investigation by the commission known as JCOPE had become an "unprecedented fishing expedition" that was politically motivated.

While the group would continue to cooperate with investigations by the U.S. Attorney and Manhattan District Attorney's office, "both politically independent investigative bodies," Laufer wrote in a 12-page letter obtained by DNAinfo New York, "we will no longer cooperate with what has obviously become a blatantly political exercise by an agency whose very independence is deeply in question."

READ MORE: Here's What We Know About the Probe Into Mayor Bill de Blasio's Fundraising

De Blasio has maintained that no laws were violated by the nonprofit and questioned whether some of the investigations he is facing are politically motivated or based on his agenda to advocate for such things as universal pre-K, affordable housing and a higher minimum wage.

"So there’s something going on here that goes beyond anything we’ve seen previously in the way such situations were treated," de Blasio said Friday on the "Brian Lehrer Show." "And I think we have to wonder about the motivations behind it, especially the fact that documents were leaked at the state level inappropriately and mischaracterizing the reality."

Laufer questioned the leak of a memo to the press regarding the investigation and the timing of a former JCOPE executive director transitioning to a senior role in Gov. Andrew Cuomo's office.

Cuomo and the mayor have engaged in a very public and long-running feud.

Further proof of bias, Laufer said, came in the form of a subpoena that requested records of the Campaign for One New York's communications with the executive and legislative branch of New York City and state government "with the inexplicable exception of seeking no records with respect to legislative lobbying targeted to" Cuomo.

"These anomalies cast serious doubt on the good faith of JCOPE in initiating and conducting this investigation," Laufer wrote.

Cuomo spokesman Rich Azzopardi denied any meddling from Albany.

"Our only knowledge of the reported investigation by the District Attorney, the State ethics enforcement body, or U.S. Attorney's Office of the mayor is what has been reported in the news," Azzopardi said.

JCOPE does have the power to go to court to try to compel the mayor's nonprofit to respond to the subpoena. The group announced in March that it was closing after good government groups called for an investigation.

“We want the documents and we want them now," Seth Agata, JCOPE's executive director, told The New York Times.

According to Laufer's letter, JCOPE is investigating whether the Campaign for One New York was required to register as a lobbyist in 2015 as it did in 2014 when the group was known as UPKNYC and focused on lobbying activities to bring universal pre-K to New York City, a successful campaign that is one of de Blasio's signature achievements.

But in 2015, the Campaign for One New York decided not to register as a lobbyist because the group was mainly focused on launching The Progressive Agenda, de Blasio's somewhat failed effort to make income inequality a central issue in the 2016 presidential elections.

The Progressive Agenda became a separate entity in July 2015 and the Campaign for One New York's work "did not trigger the statutory threshold for registration as a lobbyist," Laufer wrote.

De Blasio is facing multiple federal and state investigations over his fundraising activities. In addition to a federal investigation into whether Campaign for One New York donors, many of whom had business before the city, received anything for their donation, authorities are also examining whether de Blasio's unsuccessful bid to bring the state Senate under Democratic control in 2014 violated campaign finance and election laws.

DNAinfo New York reported earlier this week that federal authorities were scrutinizing de Blasio's 2013 campaign for possible straw donors and how a developer with business before the city said it was hard to say no when the mayor called and requested a $20,000 for one of his nonprofits in 2014.

De Blasio also hired an attorney to represent him personally in the federal and state probes and the city hired two white shoe law firms at taxpayer expense to represent the city.