For days, hacked emails to and from Hillary Clinton's campaign chairman, John Podesta, have been dripping out on the Wikileaks website. Among many other things, the emails are giving us some insight into the relationship between the Clinton campaign and a very prominent New Yorker who publicly played coy about endorsing her for six months, Mayor de Blasio. Our Courtney Gross has the story.

Back in September of 2015, Bill de Blasio was telling the media he was not ready to endorse Hillary Clinton.

"Secretary Clinton is offering a more and more powerful vision for addressing the issues that I'm particularly focused on," the mayor said last year. "I still think there is some issues we have to hear a little more on."

But behind the scenes, he was telling the Clinton campaign something else.

In an e-mail to the campaign later that month de Blasio said he was sitting down with Clinton's rival, Bernie Sanders. The mayor wrote:

"My message to him (saying this in confidence to you) is that I will always want to work with him in the future and will never have a bad word about him, but won't be supporting him in this campaign."

In 2015, de Blasio withheld his endorsement from Clinton for months after once being considered a Clinton confidante. He managed her run for U.S. Senate. Bill Clinton administered his oath of office.

Emails posted on Wikileaks over the past several days from the account of the chairman of the Clinton campaign provide an inside look at how this relationship has evolved.

In 2014, one of Clinton's closest aides, Huma Abedin, wrote someone else needed to inherit this quote "relationship."

As de Blasio withheld his endorsement, he also updated the campaign chairman on what he said about her.

"I think it's important for people to hear how she will address income inequality," the mayor said in May last year.

The next day de Blasio sent Clinton campaign chairman John Podesta an email. The subject line: "optimistic." The mayor said he used the word "400 times" during the interview.

After he gave Clinton his endorsement in October of 2015, he then offered so-called constructive criticism.

After a debate, the mayor wrote: "Hillary was fantastic on the gun control answer, then totally blew the mass incarceration question. Why on Earth did she say 'Are you going to ask Senator Sanders that question?' instead of just addressing the issue. When she makes it about her, she loses the high ground."

A spokesman for City Hall said these emails are not embarrassing, and then he declined further comment.