He employed Dewey Square to focus on Hispanic and black community leaders and politicians based on a belief that because many of the individuals who are recruited as distributors by Herbalife are minorities, taking on the company might in some way help the Latino community. Separately, the lobbyists and grass-roots organizers set up meetings with major consumer groups.

Enlisting Allies

A wave of additional letters started to be sent to federal regulators by groups like the Hispanic Federation and the National Consumers League. Each person contacted by The Times acknowledged in interviews that they wrote the letters after being lobbied by representatives from Pershing Square, or said they did not remember writing the letters at all. Mr. Ackman’s team also then started to make payments totaling about $130,000 to some of these groups, including the Hispanic Federation — money he said was being used to help find victims of Herbalife. The pitch by Mr. Ackman peaked in early February, when nearly 30 people affiliated with Latino advocacy and church groups, several of whom had joined the cause after being briefed by consultants hired by Mr. Ackman, flew to Washington to meet with members of Congress and the head of the F.T.C., again pressing for investigators to take action against the company.

Three of the nonprofit group leaders who participated in the event, from Massachusetts, Illinois and Washington, said they took part because they also believed that Herbalife was taking advantage of the working class and poor.

“At the end of the day, these people are becoming millionaires off the back of the people in the shadows,” said Julie Contreras, the president of the Lulac chapter in Waukegan, Ill., who traveled to Washington for the event, adding that she had not taken any money from Mr. Ackman or anyone on his team.

Mr. Ackman did not publicize his role in helping generate these letters or rallies, or the fact that his consultants in many cases wrote the language that is used in these letters, but his team still issued news releases noting that yet another group had called for an investigation.

In Washington, Mr. Ackman’s efforts bore fruit on Jan. 23, when Mr. Markey’s office, which Mr. Ackman had lobbied himself and which had been provided with detailed information about Herbalife by Mr. Ackman’s team, sent letters to the S.E.C. and F.T.C., calling for investigations of the company. A little more than a half-hour after the stock began trading that day its value fell by 14 percent.

The letter sent by Ms. Sánchez in June, which Mr. Ackman discussed at the dinner, did not move the stock. Ms. Sánchez’s office acknowledges that it sent a copy of this letter to Mr. Ackman’s team a month before it issued its news release on the matter, and says that it backdated the letter when making it public because The New York Post reported its existence a week after the dinner. The dinner itself was reported in August by The Wall Street Journal.A spokeswoman for Ms. Sánchez said backdating the news release was not inappropriate, as the office considered the document public when it was sent to the F.T.C.