The MTA promises to have the first phase of the Second Avenue Subway done by December 2016, but some elected officials on the Upper East Side said the agency will have to overcome a few challenges to meet that deadline.

U.S. Rep. Carolyn Maloney, City Council members Ben Kallos and Dan Garodnick and representatives for other elected officials gave an update on the project at a news conference Wednesday and said they would push the agency to work on areas of concern regarding the line.

Maloney said the first phase of the nearly project, which will create stations on Second Avenue and 72nd, 86th and 96th streets as an extension of the Q line, can't wait another year.

"The most important thing we can do for economic development and quality of life is finish the Second Avenue subway," she said.

Although work on the first phase is 83% done, Maloney said costs are rising from $35 million to $45 million a month and there have been delays on electrical and track work. The biggest factor is the 86th Street station entrance which is behind schedule and caused the MTA to call for more workers and longer hours of construction.

The congresswoman said the Federal Transit Administration gave a date for 2017 for completion during a recent hearing but a spokesman for the MTA said they are still targeting December 2016.

Maloney said she is sticking with the MTA's estimates but said she and the community will monitor its progress on the delayed work. Construction created noise and pollution problems for Upper East Side residents and many businesses have been negatively impacted by the eight years of construction work.

Later this month, she plans to release her annual report card on the project, which will ultimately create a new line between 125th Street and Hanover Square.

"It keeps and keeps stalling and stopping but we won't stop until it opens," she said.