Tributes have been paid to former New York mayor Ed Koch, who died early Friday morning at the age of 88.

With his trademark phrase "How'm I Doin?," Koch is credited with bringing the city back from fiscal ruin in the 1970s. He served three terms as mayor and lost the Democratic nomination for what would have been a record fourth term in 1989. After a year of ill health, he passed away at around 2am on Friday morning at NewYork Presbyterian Hospital.

Read More: Ed Koch not popular with many Irish during his career

"In many ways Ed Koch never stopped being mayor," Police Commissioner Ray Kelly said.

"He was personally engaged in the issues of the day, including those involving the Police Department, frequently seeking information from us and offering his opinion personally and in writing,” Kelly added.

City Council Speaker Christine Quinn, who was endorsed by Koch for her 2013 mayoral run, said his legacy means he will always be a part of New York.

“He once said, 'I don't want to leave Manhattan, even when I'm gone. This is my home.' Ed Koch will never leave New York City. He will exist forever in our hearts, and in the millions of lives he touched,” Speaker Quinn said.

New York Governor Andrew Cuomo said Koch embodied the highest ideals of public service.

He said: “His life was dedicated toward making New York— the city and our state — a better place for all."

Senator Chuck Schumer said modern day New York, would be nothing today without the Democratic Representative.

"Every atom in his body lived, breathed, spoke and exuded the city. He helped save the city and, perhaps most important of all, gave it confidence when it was beginning to doubt itself, which helped pave the way for the growth and prosperity we're still experiencing today," Schumer said.

In a statement Cardinal Timothy Dolan, the archbishop of New York, spoke about Koch’s connection with the Catholic community.

“It is, perhaps, some measure of the respect that Ed Koch – a proud, Jewish man, as he described himself to me – continued to hold among Catholics that a seat was always held for him at Midnight Mass in Saint Patrick’s Cathedral, and, at the annual Alfred E. Smith Dinner, the largest ovation invariably went not to the evening’s guest speaker, not to the Archbishop of New York, but to Mayor Koch.”

The Cardinal added: “He will have special place in my prayers, and in those of the Catholic community he loved and worked closely with, this weekend.”

Ray Flynn, the former Mayor of Boston and U.S. Ambassador to the Vatican said Koch personified New York City.

“He just wasn't the Mayor of New york, he was the heart of New York City. “

“Irish Catholic Cardinals loved him, Rabbis loved him, the homeless loved him, and the cooks and waitresses down on Little Italy loved him. Even Pope John Paul II loved him. The mayor of Boston even named an outdoor garden in a Jewish Elderly Development in Boston after him. Koch was a credit to his proud Jewish heritage and I was lucky to learn from him,” Flynn said in a statement.