NEW YORK (CBSNewYork/AP) -- De Blasio managed Clinton's 2000 Senate campaign and worked at the Department of Housing and Urban Development under the former secretary of state's husband, ex-President Bill Clinton.
Former President Clinton even swore de Blasio into office at his City Hall inauguration last year.
Former President Clinton even swore de Blasio into office at his City Hall inauguration last year. And CBS2 Political Reporter Marcia Kramer reported, de Blasio and Hillary Clinton were cordial at the mayor's inauguration.
But the mayor initially refused to endorse Hillary Clinton, saying he needed to hear more detailed policies, most notably about income inequality.
Appearing on "Meet the Press'' the April morning of Hillary Clinton's campaign announcement, he said that unlike other New York politicians, including both senators and Gov. Andrew Cuomo, he would not automatically be backing the former Secretary of State.
"I think she's one of the most qualified people to ever run for this office and, by the way, thoroughly vetted,'' de Blasio said then. "But we need to see the substance.''
He stuck to that script in the coming months even as criticism mounted within the party. He also stuck to it during the rise of Bernie Sanders, who shares many of de Blasio's left-leaning views.
The mayor also moved toward making himself a national figure on liberal issues, particularly on the fight against income inequality, and founded The Progressive Agenda Committee, which is hosting a presidential forum in early-voting Iowa this December.
But polls reflected that many New Yorkers felt that de Blasio was prioritizing the national over the municipal and many of his advisers in City Hall urged him to simply take the plunge and endorse Clinton.
On Friday, he finally did, and he offered a spirited defense of his further boss.
"There's a lot of spine there and a lot of steel there,'' said de Blasio. "She has said what she believes in. This is a very sharp, progressive platform and she has the ability to follow through on it.''
Still, on the "Morning Joe" show where he endorsed Clinton Friday, de Blasio also said some things about Sanders.
"Bernie Sanders has moved the discussion in this country in a very productive way, and we needed that," the mayor said.
And now, the mayor's Halloween eve decision to endorse her campaign after months and months of public dithering may have a trick-or-treat quality to it, according to experts.
"At this point, I don't think an endorsement like that is going to matter much," said Jeanne Zaino of Iona College.
Zaino said de Blasio's six-month delay in endorsing Clinton monumentally reduced the value of the endorsement. But it also came as a local poll gave de Blasio low marks in handling city issues – making some wonder whether the gift de Blasio put in Clinton's Halloween bag was a savory candy or a rotten apple.
The Quinnipiac University poll found that 61 percent of New Yorkers disapprove of de Blasio's handling of poverty and homeless, while 28 percent approve. A total of 53 percent said quality of life is getting worse rather than better while 14 percent disagree, and 59 percent of those polled disapproved of the mayor's handling of crime while 32 percent approved.
The margin of error in the poll, released Thursday, was plus or minus 2.9 percent.
Some think de Blasio endorsed Mrs. Clinton Friday in an attempt to get her and others to attend his Iowa presidential forum – an event in which few have expressed interest. That too may be a miscalculation, according to Zaino.
"I'm not certain there's going to be a lot of reasons for her do to it," she said. "We may find that the campaign says, 'You know, unfortunately, we have scheduling issues.'"
A spokeswoman for de Blasio's forum said invitations to the top five candidates in each party will go out next week. But it could turn out to be a haunted house, since there are only three Democrats left – Clinton, Sanders, and former Maryland Gov. Martin O'Malley – and Republicans may not think it is good for their political health to appear with the liberal de Blasio.
Speaking of Halloween, the de Blasios were going as the New York Mets for their holiday party. First Lady Chirlane McCray was going as Curtis Granderson, and the mayor as Yoenis Cespedes.
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