Elizabeth Ferrara Gary LaBarbera, president of the Building and Construction Trades Council said the plan would create much-needed construction jobs.

In the first rally of its kind, advocates of N.Y.U.’s controversial expansion gathered yesterday at City Hall calling on Borough President Scott M. Stringer to approve the plan.

About 35 people, business owners, union leaders, and construction workers among them, attended the roughly 15-minute gathering in support of the university’s proposal that would add four new buildings south of Washington Square Park.

“We’re here today asking Borough President Stringer to recognize that N.Y.U.’s growth strategy is an essential part of securing the financial future of small businesses in Greenwich Village,” said Tony Juliano, president of the local Greenwich Village-Chelsea Chamber of Commerce, which represents around 200 businesses in surrounding neighborhoods.

It was clear that the approval for the plan dubbed N.Y.U. 2031 is getting down to crunch time. The event amounted to a formal endorsement from the Building and Construction Trades Council, which is led by the influential Gary LaBarbera.

“N.Y.U.’s plans for Greenwich Village will create thousands of good unionized building and construction jobs and generate increased economic activity across the city,” said Mr. LaBarbera.

According to a press release from the rally’s organizers, the expansion plan would generate an additional 2,400 jobs every year for the next 20 years and roughly $27 million annually in city taxes over the next 20 years. Similar estimates for other major developments, like the Atlantic Yards project in Brooklyn, have been met with a great deal of skepticism.

A small business owner echoed the enthusiasm for N.Y.U.’s expansion.

“N.Y.U. is vital to the economic future of the neighborhood and would help businesses like mine,” Steven Cervino, owner of Sigma Burger Pie on West Third Street said.

Still, the attendees at City Hall today were miniscule in comparison with the 200-person crowd that packed St. Anthony of Padua Church last month when Community Board 2 voted to recommend disapproval of the plan. Not surprisingly, those opponents have been lobbying Mr. Stringer as well.

“N.Y.U.’s presence has become increasingly dominant in more and more areas and ways,” wrote Andrew Berman, the executive director of the Greenwich Village Society for Historic Preservation in a letter to Mr. Stringer last week. “This balance will only continue to shift in that direction unless N.Y.U.’s growth in the Village and immediate vicinity is capped.”

Another opponent, Mark Crispin Miller, a professor of media studies and a leader of N.Y.U. Faculty Against the Sexton Plan, scoffed at the economic necessity of the plan. “N.Y.U.’s expansion will create construction jobs wherever it takes place. It doesn’t have to be in Greenwich Village,” Mr. Miller wrote. “And far from doing local merchants any good, the Sexton plan will put them out of business, by jacking up their rents and driving off their older customers, while making them compete with N.Y.U. for all the student trade.”

Mr. Stringer’s ruling is expected by April 12. The plan will then go before the City Planning Commission, followed by the City Council for final approval.

Update | 10:35 a.m. Added additional statistics regarding the economic benefits of the project.