When members of District Council 37 gathered to endorse Bill Thompson in August, a palpable sense of anger filled the basement of the union’s headquarters.

For over a year, relations with Mayor Michael Bloomberg had been on a sharp decline. And though the press conference was in the middle of the day, DC 37 members clad in green T-shirts filled the room, unleashing their fury about the mayor.

“He’s changed! He’s changed!” exclaimed District Council 37 executive director Lillian Roberts.

But now, following Bloomberg’s narrow re-election win, Roberts will have to sit down in March with the man she so staunchly opposed and begin hashing out a new contract for the 125,0000-member public employee union.

In doing so, Roberts will be in a different position than many of the city’s other public-sector unions, who either sat out this year’s mayoral election or endorsed Bloomberg. Some feared privately that crossing the heavily favored mayor could effect their upcoming contract negotiations.

Nonetheless, Roberts said she still believes any animosity from the mayoral campaign would not carry over.

“This was never personal,” she said.

“This had to do with making the best decisions we could for our members and getting attention to our problems. And I think the same attitude applies to the mayor. I think he’s bigger than that.”

Roberts herself is up for re-election on Jan. 26 and faces what could be a tough challenge from Claude Fort, president of the Local 375 Civil Service Technical Guild.

Fort said that under Roberts the union has lacked a long-term political strategy that could have helped fight layoffs in light of the $5 billion budget gap.

He also expressed skepticism that Roberts’ rhetoric about Bloomberg would be forgotten so quickly by the administration, which has developed a reputation in some quarters for remembering such slights.

“She took it too personally,” Fort said.

“She had a personal vendetta.”

A group of anti-Roberts candidates running on a slate called “Members Deserve Better” are arguing that Roberts has soured relations with the mayor, and that new leadership is needed.

“She attacked Bloomberg, and everyone was scratching their heads,” said Arthur Schwartz, an attorney representing a number of candidates running on the slate. “Instead of being the first to get a new contract, I think DC 37 will have to wait the longest for a new contract, and will suffer the worst layoffs.”

Over the past four years, DC 37 has received generous 4-percent raises. But in making their endorsement decision this year, leadership decided it could no longer stomach the administration’s $9 billion in annual spending on outside contractors, thousands of public employee layoffs and opposition to a bill lifting residency requirements for DC 37 workers.

State Sen. Diane Savino, a former DC 37 staffer and chair of the Senate Civil Service committee, argued that the union had made the right call in endorsing Thompson.

“The mayor has not been particularly friendly to labor over the past year and a half, and DC 37 members bore the brunt of it,” Savino said. “You don’t endorse somebody when they’ve got their foot on your neck—and they were going to have a hard time bargaining with the mayor anyway.”

Some within the union are now also taking solace in the fact that the United

Federation of Teachers does not seem to be getting many concessions in its own current negotiations despite remaining neutral in the mayor’s race.

The union also does not have especially strong relations with Council Speaker Christine Quinn: they declined to endorse Quinn in her Council re-election campaign, citing Quinn’s failure to show up for a candidate interview. (The union made no endorsement in that race.)

But the union’s political director, Wanda Williams, said that she expected the Council as a whole to work on behalf of DC 37, should Bloomberg propose deep cuts in the DC 37 workforce. She noted that the union supported 11 of the 13 newly elected Council members, and many other returning members.

“We have a lot of support in the Council, and we see it as a counterbalance,” Williams said.

Opponents of DC 37’s current leadership argue, however, that the union does not wield the political clout that it once did. They hark back to the city’s last major financial crisis, in the mid-1970s, when the union’s president, Victor Gotbaum, brokered an agreement that helped save the city from fiscal ruin. Now, the union is ill equipped to similarly deal with this fiscal crisis, Roberts’ critics argue.

When Roberts was elected, it was done with the expectation that she would serve for 18 months, while warring factions in the union found a long-term replacement. Instead, seven years later, she is again running for re-election, in her 80s and with no clear successor in place.

Over her tenure, Roberts has been able to foster a close relationship with many in the rank-and-file, exuding a kind of grandmotherly warmth. But her personal popularity has not helped DC 37 become more united, said one high-level labor insider who works closely with the union.

“The warring factions that existed when she came in still exist today,” the insider said. “There’s no understanding that there’s 125,000 people depending on you to strategically deal with cutbacks and see them through a fiscal crisis.”

Opponents of Roberts say the union has been weakened by a leadership structure that does not brook dissent from its local union leaders, and which instead seeks retribution against those who are disloyal. They also assert that Roberts has not cleaned up corruption as promised, citing a recent scandal involving the 2054 College Assistants Union. The president of the union allegedly used union funds to throw a $30,000 party, spent $41,000 on a Cadillac and blew $1 million more on bad investments.

Roberts declined to discuss the leadership election or internal union matters.

Council Member Letitia James, who has worked closely with the union, said she believes Roberts has done an excellent job, especially in gathering information on Bloomberg’s use of outside contractors, which James has used as ammunition to rail against cuts to the city workforce. James added that DC 37 also remains a force to be reckoned with politically and said the talk of disunity under Roberts was motivated by other factors.

“The 800-pound gorilla in the room that nobody wants to talk about is sexism and ageism,” James said. “The discussion about not being able to organize the members is a disguise for that. But I dismiss the notion that Lillian is past her prime. She still outpaces me and many of members of the Council who are younger than me.”

If re-elected, Roberts said one of the union’s top priorities would be to continue fighting the outsourcing of union jobs to private contractors. She also wants reform in what she believes are civil service testing rules unfairly placed on DC 37 members, but not other public employees.

In addition, Roberts said that after a heated campaign, she hopes to establish better relations with the mayor.

“I’m very concerned about some of what has happened,” she said, “and I’m hoping that in the third term, we’ll have better communication and a better understanding.”