The Elm City’s longest-serving mayor is already eyeing another term.

Mayor John DeStefano Jr., who won a record 10th term by a modest 1,600-vote margin last November, began showing signs of campaigning this summer. As Yale’s labor unions — which have opposed the mayor’s fiscal policies in recent years — tested the political waters for possible challengers of their own, DeStefano’s reelection committee racked up donations far in advance of next year’s campaign season.

The DeStefano 2013 campaign can be traced back to a May birthday celebration at Anthony’s Ocean View restaurant, with tickets ranging from $150 to $500 per person to “support” the mayor’s reelection. DeStefano also paid a visit to Bella Vista senior housing complex in mid-August sporting bags that read “DeStefano for Mayor 2013.”

A July campaign filing by the DeStefano for Mayor committee indicates that the mayor raised over $75,000 from individual contributions between April and June, plus an additional $5,000 from group donations. According to the filing, many of the individual contributions came from city employees — including city spokeswoman Elizabeth Benton ’04, chief administrative officer Rob Smuts ’01 and corporation counsel Victor Bolden — members of the Board of Education, agencies associated with the city like the New Haven port authority and contractors doing business with the city.

Carter Winstanley, the developer whose company is set to build a $100 million biotech building in the modified Route 34 corridor, donated the maximum of $1,000 towards DeStefano’s reelection. While DeStefano established a public financing system in 2007, he abandoned the program last year and defeated challenger Jeffrey Kerekes, who relied solely on public financing, after outspending him by a 20 to 1 margin.

While nobody has declared a bid to oppose DeStefano, some groups are already trying to determine whom to support. A phone poll by Yale’s unions last week asked New Haven residents for their opinions on DeStefano, Kerekes, State Reps. Gary Holder-Winfield and Toni Walker, State Sen. Toni Harp, Board of Aldermen President Jorge Perez, former city economic developer Henry Fernandez and Greater New Haven NAACP President Jim Rawlings.

The poll focused many of its questions on Perez, who, as president for seven of the 25 years he has spent on the Board, is one of the city’s best known politicians. Organized labor demonstrated its political prowess last November, when aldermanic elections gave the Board a majority of pro-labor members, and union endorsements could be key in next year’s mayoral race.

While labor-backed candidates were elected in an anti-mayor climate, DeStefano supported many of their proposed policies after the election, including a return to a community policing strategy and the creation of a “jobs pipeline” to connect New Haven residents with local jobs. Labor- and City Hall-backed aldermen have largely cooperated on legislative initiatives, passing DeStefano’s proposed city and federal grant budgets with minimal controversy last spring.

On Oct. 4, DeStefano will become the longest-serving mayor in city history, surpassing Elizur Goodrich, who served from 1803 to 1822.