NEW YORK (Reuters) - Former New York City mayor Ed Koch died on Friday at age 88 after a year of repeated hospitalizations, a spokesman for Koch said.

As mayor from 1978 to 1989, the forceful, quick-witted Koch, with his trademark phrase "How'm I Doing?," was a polarizing figure and the city's constant promoter.

Koch died at about 2 a.m. (0700 GMT) at New York-Presbyterian hospital, the spokesman for Koch said.

Koch was credited with lifting New York from crushing economic crises to a level of prosperity that was the envy of other U.S. cities. Under his leadership, the city regained its fiscal footing and undertook a building renaissance.

But his three terms in office were also marked by racial tensions, corruption among many of his political cronies, the rise in AIDS and HIV, homelessness and a high crime rate. In 1989, he lost the Democratic nomination for what would have been a record fourth term as mayor

(Reporting by David Storey and Edith Honan, Editing by W Simon)