“I once again apologize for my actions,” he said in the statement, “and for the pain and disappointment those actions caused my family and the many people who supported me during my career in public life.”

Mr. Spitzer, reached later on his cellphone, said that he would have no comment beyond the statement. Michele Hirshman, a partner at Paul, Weiss, Rifkind, Wharton & Garrison who is Mr. Spitzer’s lead counsel, declined comment on Mr. Garcia’s decision through a spokeswoman.

The announcement by Mr. Garcia, a Republican who has served as the United States attorney for the Southern District for three years, comes as he prepares to leave the post for private work.

An announcement in the case, which earlier in the year had drawn criticism from some Democrats who suggested that it was politically motivated, was expected to follow the election, although perhaps not so rapidly.

Several people briefed on the case said that in recent months, Mr. Spitzer’s team of lawyers made several presentations to prosecutors from the Public Corruption unit in Mr. Garcia’s office and their superiors to argue against charges.

The presentations, they said, focused on the defense team’s argument that no campaign money or state funds were involved, that Mr. Spitzer did not illegally structure the transactions to pay the prostitutes, and that charges were not warranted under the Mann Act, which prohibits transporting people across state lines for the purpose of prostitution.

Image Gov. Eliot Spitzer, with his wife, Silda, at a news conference on March 10. He quit two days later. Credit... Sara Krulwich/The New York Times

Mr. Spitzer, the square-jawed crusader who promised to bring ethics to Albany, was elected governor in 2006 by a wide margin after eight years as state attorney general. A Democrat, he made his reputation as a prosecutor who tackled white-collar corruption so single-mindedly that people nicknamed him “the sheriff of Wall Street,” and his admirers hoped the State Capitol would be a steppingstone to national office.