The leader of the developer-backed advocacy group for the Brooklyn-Queens Connector, the mayor’s streetcar project, is stepping down.

Ya-Ting Liu, executive director of the Friends of the BQX, plans to leave the group on Friday after 18 months in the position, but before significant planning or outreach for the project has been completed. A spokesperson said that Liu felt this was an appropriate time to step down, and Liu did not immediately return calls for comment.

Deputy director Jessica Schumer, the daughter of Senate Minority Leader Chuck Schumer, will serve as interim executive director until the position is filled. Schumer had served as the policy director for Tim Kaine on Hillary Clinton’s 2016 presidential campaign and had worked in the White House during the Obama administration.

Mayor Bill de Blasio unveiled his plan for a $2.5 billion streetcar in his 2016 State of the City address, though the project has remained relatively stagnant since a series of early public input sessions were held last year. The streetcar would run along a 16-mile route from Sunset Park to Astoria, although many aspects of the plan remain unclear, such as route details, fare integration with MTA services and its funding mechanism through value capture financing.

During her tenure, Liu built the group’s board of directors, with representatives from real estate firms, institutions and civic groups. It also includes Jay Walder, the CEO of Motivate, which operates CitiBike, and MTA Chairman Joseph Lhota.

“As a seasoned transit advocate, Ya-Ting’s primary goals were building a robust coalition of supporters and future riders, all of whom believe in a more equitable transit system that reflects the needs of neighborhoods from Sunset Park to Astoria. We’re proud to say she accomplished just that,” said a spokesman for Friends of the BQX in a statement. “Ya-Ting’s passion and drive helped make this all possible. Just as importantly, her tenure has laid the groundwork for our continued advocacy in the months to come as work on the project begins.”