Complications and delays have beset Mayor Bloomberg’s planned expansion of the city’s 311 line.

Days after winning a second term in November, Mr. Bloomberg announced that the city would bolster the municipal help line to include information about social services and referrals to thousands of nonprofit groups. The 311 line currently directs callers only to city agencies and organizations that have contracts with the city.

The initiative was seen as an effort to deliver immediately on a campaign promise, and the Bloomberg administration set an ambitious timetable with plans to have the expanded system in place within a year.

But a number of factors, including the departure of a key city commissioner, have impeded the project, forcing the city to scale back its earlier projections. While a city-led planning committee is meeting regularly, officials now say that only a part of the expansion — a referral service for seniors — will be ready by the fall. There is no timetable for completing the rest of the initiative.

“The project is going to be rolled out in phases, and we fully expect to hit the one-year commitment,” a spokesman for the mayor, Paul Elliott, said, citing the new service for seniors as the initial stage.

The expanded capability of 311 is meant to equip the city with the same features offered by 211, a social service hotline now available in more than half the country, and which is in development for the rest of New York State. Nonprofit groups and other advocates have long pushed for the city to adopt 211, but Mr. Bloomberg has opposed that effort, saying it would create confusion and defeat the “one-stop-shopping” purpose of 311.

Instead of helping New Yorkers navigate the bureaucracy of municipal government, the new features would assist callers in finding such things as free legal advice or services for the disabled or infirm that are not offered by the city.

“It’s a different type of caller, between asking about alternate side of the street parking and a caller who has no food and needs to find a resource to eat,” said Nancy Miller, a member of the planning committee and the head of VISIONS, a nonprofit for the blind and visually impaired.

The city is spending $10 million to enlarge 311, in addition to a $3.8 million grant from the state.

Using its unmatched database of 2,500 social service agencies, United Way had developed the 211 line for other cities, and Mr. Bloomberg had said the city would partner with the organization for its expansion of 311.

But the nature of United Way’s role in the project has also changed. The organization is heading up the nonprofit side of the planning process, but whether it will be charged with implementing the new services is unclear.

A consultant working on the project for United Way of New York City, Gary Wartels, said the city had determined that instead of simply contracting with United Way, procurement rules required an opening bidding process and a request for proposal, which has not been sent out. Mr. Elliott would not confirm those details, saying the process was still being reviewed.

The departure earlier this year of the commissioner of the Department of Information Technology and Telecommunications, Gino Menchini, also set the project back. Now shepherding the 311 expansion is the deputy mayor for health and human services, Linda Gibbs.

The planning committee is working with representatives of more than a dozen nonprofits to figure out how the new referral service will work. Members said they were happy the project was moving forward and indicated that the administration may have been overly ambitious with its initial timetable for such a complex undertaking. Among the details that have yet to be determined is who will staff the new call services, how referrals will be made and which nonprofits will get them.

“It’s worth the time and effort to make sure the system works so that the people in need get the help they need,” Ms. Miller said.