"Charlie Rangel is a giant," said former Mayor David Dinkins.
"He's a man who has served not only the 15th Congressional District but this city. He's served this nation. .... There's nothing to be gained by seeking to further humiliate this great man."
The House ethics committee voted 9-1 on Thursday to recommend censure for Rangel after the same panel convicted him of 11 violations, including failure to pay taxes on rental income from a villa in the Dominican Republic. Censure is the most serious congressional discipline short of expulsion.
The full House is expected to vote after the Thanksgiving break.
State Assemblyman Keith Wright said Congress should vote "no."
"I will be making phone calls," Wright said. "All of us will be making phone calls. And we will urge all congresspeople throughout this nation to vote no on this process."
Rangel told the ethics panel that he was not a crooked politician out for personal gain.
On Sunday, Rangel said through Twitter, "The final decision has to be made by the week after next by the House of Representatives. So thank you for your prayers and support over the years. I need them now more than ever."
Supporters at Sunday's news conference in Harlem said the 20-term Democrat had done nothing illegal.
"He had sloppy bookkeeping, yes," said City Councilwoman Inez Dickens. "Illegal, no."
The 80-year-old Rangel has spent 40 years in Congress and has steered millions in federal funds toward the revitalization of Harlem, where he is a beloved figure for many.
"Let's move forward in this community, in New York City," City Comptroller John Liu said. "Let's not forget the incredible, incredible amount of service that Charles Rangel has rendered for this community and for all of New York City."
The Rangel supporters ended their news conference outside the Mother AME Zion Church by singing "We Shall Overcome."