Mayor Bill de Blasio's 2013 campaign was given a massive boost when the city's largest union endorsed him, but that union hasn't spent a dime on his re-election campaign. NY1's Courtney Gross takes a look at what happened to that relationship when de Blasio became mayor.

Local 1199 was way ahead of the game. The city's largest union, representing 200,000 health care workers, was endorsing Bill de Blasio for mayor. 

"Members believe that politics is the way for them to have a better lifestyle," George Gresham, president of Local 1199 SEIU, said in May 2013.

It was a lifestyle supported by Bill de Blasio, who quickly capitalized on priorities for the union, like trying to prevent the closure of a hospital in Brooklyn. 

"We have to stop hospital closures in this city," de Blasio said in July 2013. "People are going to be much sicker if we keep losing our hospitals."

The endorsement was early and major. It helped propel the then-public advocate from protests and handcuffs to City Hall. 

This is a look at what happened to that relationship between a powerful union and the progressive executive charged with protecting its cause. 

Under the Freedom of Information law, NY1 received hundreds of pages of emails from the first two years of the de Blasio administration detailing how close the union and the mayor really were. 

The emails are between the union's former political director Kevin Finnegan and top city officials. Many of them at one point previously worked with or for 1199, setting up the union to have the inside track on the inner workings of city government.

"We're not interested in owning City Hall and we're not going to own City Hall," Finnegan said in 2013. "Don't believe that Bill de Blasio got elected because of us. I think that we endorsed Bill de Blasio because we thought he was the best candidate and we thought he could win."

What these documents show is, the doors to City Hall were wide open for the union. It got a heads up about announcements, or the union crafted talking points for the mayor. 

Finnegan passed along resumes to the mayor's chief of staff and acted as a conduit to push the mayor's message. 

About a month into the administration, the mayor's top political aide emailed his press secretary: "Kevin Finnegan got a call on Wall Street Journal on labor negotiations with DEP. He will say whatever we want."

In the wake of a tragedy, the assassination of two police officers in December of 2014, and heavy criticism from the police union, the administration asked for help.

A City Hall aide wrote: "We really need you to push support for a 'deep breath,' time to reflect and grieve."

The aide asks the union to issue a statement. The next day, it did, calling for a suspension of all protests. 

It's an alliance not surprising to those close to City Hall and the union.

"They have been aligned for a long time," said Josh Gold, a former Local 1199 SEIU staffer. "They share the same progressive vision for the future of the city. The members of the union care about the same things that the mayor cares about."

Finnegan left the union in early 2016. When NY1 spoke to him for this story, he characterized his relationship with de Blasio's City Hall as better than previous administrations.

That's despite high-profile losses for the union in de Blasio's first years in office, like Long Island College Hospital. 

City Hall and the union were in regular communication about a plan to keep Long Island College Hospital open. 

The deputy mayor wrote to Finnegan about the hospital in the summer of 2014. "Can we grab a few minutes today? I think the issues at LICH may be soluble but we are going to need some calm heads."

Finnegan says much of the negotiations were on the state level. His communication with City Hall at the time was purely to keep de Blasio officials in the loop. 

Nonetheless, those communications were still the subject of an investigation, an examination of the sale of the hospital and its eventual evolution into condos. 

Which brings us to another scandal. 

Local 1199 helped push the original sale of a hospice center on the Lower East Side from nonprofit to for-profit hands. The hospice, known as Rivington House, was eventually flipped again thanks to the city lifting a deed restriction. It was a major scandal for de Blasio and is still under investigation. 

The emails from 1199 on the subject started in January of 2015.

When the first sale went through, City Hall quickly notified the union. In February of 2015, a City Hall aide wrote: "We completed the Rivington House transaction late this afternoon. Many thanks to you for your help."

Finnegan responded with: "Yahoo!"

When it became clear the building was on track to be flipped again, it was Finnegan who told City Hall, "It will indeed undoubtedly be luxury condos."

It was sold to a developer for luxury condos two months later. 

Observers say both are major defeats for the union.

"There's been some losses," said Daniel DiSalvo of the Manhattan Institute. "Primarily, things that you could say that Long Island College Hospital and Rivington House were things that maybe the union hoped would see different outcomes than what ultimately came to pass." 

Throughout this, the union was still a major supporter of the mayor, contributing a total of $525,000 to his political nonprofit groups, the Campaign for One New York and United for Affordable NYC.  

But so far, the union has been silent this election cycle. 

While it has donated thousands of dollars to City Council candidates, the union hasn't contributed to the mayor's re-election campaign. It has not endorsed him either. 

Sources tell NY1 the union's failure to endorse could be attributed to someone else. One source says Governor Andrew Cuomo's team pushed the union to delay an endorsement of the mayor as part of his ongoing feud with City Hall. 

The state controls far more of the union's business, so siding with the governor is, perhaps, a smarter move politically. 

"Long-term, the governor is more important to SEIU 1199 since most, a lot of what supports the big portion of hospital and nursing home revenues in the city and statewide is Medicaid dollars," DiSalvo said.

Which are controlled by the state. 

Sources say the silence may also be a sign of a leadership vacuum, since Finnegan left the union last year. 

In response to this story, a spokesman for Local 1199, sent a statement, which reads, "Given the need to focus on the dire threats from Washington to healthcare funding and services, we have not yet scheduled major endorsement events in citywide races. We expect to do so shortly."

A spokesman for Local 1199 also told NY1 that union officials are proud of the work they have done with the mayor in his first term. 

De Blasio's campaign also sent a statement, saying it would be proud to have the union's support again. 

The governor's office did not comment for this story.