As New Haven Mayor John DeStefano Jr. shakes up his City Hall staff this week as he refocuses on New Haven, two local residents have come forward with hopes of ending his seven-term stint as mayor before the end of next year — and one candidate might like to curb Yale’s relationship with New Haven while he’s at it.

Willie Greene, a former Newhallville Ward 21 alderman who has attacked Yale for plotting a “takeover” of city neighborhoods, filed the requisite paperwork on Monday to oppose DeStefano in the 2007 Democratic primary for mayor. Since New Haven is an overwhelmingly Democratic city, mayoral races historically have been won by the primary victor.

Both Greene and Thomas Holahan ’63 — another former alderman who ran for mayor as an independent in 2005 and filed to run again in 2007 as a Democrat — will face a formidable challenge in unseating DeStefano, who has been undefeated in local elections for more than 13 years. Greene could not be reached for comment Monday, but his mother said she is proud of her son for running.

“I think he’ll make a good mayor, because he does the right thing now, and I think he’ll continue doing the right thing,” she said.

Though Greene prevailed by several votes this past Election Day to lead the Ward 21 Democratic town committee, some city officials and aldermen said they view his candidacy with skepticism, especially after the Dixwell Community “Q” house had to close down during his tenure as its executive director. These critics say Greene has not always done the “right thing” while in office, but they declined to discuss specifics beyond the collapse of the “Q” house.

Greene has said in the past that he disapproves of the extent of Yale’s relationship with New Haven.

“Yale is buying up property and fencing in Dixwell,” he told the New Haven Advocate in 2002. “They don’t want to see poor people. The city is not working aggressively enough to see there’s real affordable housing.”

Douglas Rae, a Yale professor who teaches a course on New Haven, said momentum might be on the side of DeStefano foes — more of whom are expected to file to run soon — in 2007.

“I think there may be momentum for a change of leadership in the city,” Rae said. “There’s a morbid life cycle to being mayor. You get better and better for 10 or 12 years and then you get a little bored with it and you go onto bigger things.”

DeStefano ran for governor unsuccessfully this past year, finding it impossible to overcome the popular Republican incumbent, M. Jodi Rell. During this time, DeStefano said, he found it “hard” to manage both campaigning in an uphill race and running the city, which Holahan cited as a factor that inspired him to run again. He also criticized DeStefano for consistently raising taxes and not engaging in proper fiscal planning, calling the city a financial “mess.”

“I’ve long felt that the mayor has not run the city properly,” Holahan said. “I think 12 years is a long time to be in office.”

Holahan has tried to become affiliated with the Green Party ticket in the past, but he said it “didn’t work out.” This is the first year the former New Haven high school physics and math teacher is running as a Democrat.

DeStefano said on Sunday that he has returned to the city with “the same level of enthusiasm” and “sense of urgency” he says he had while running for governor. But Derek Slap, his spokesman, said the mayor has no immediate plans to start campaigning aggressively for mayor.

“There will be an appropriate time to get into campaign swing, and to talk about the ideas of each candidate and for the mayor to talk about his record of accomplishment,” he said. “Right now, he’s focused on running the city.”

As part of this refocus, DeStefano will be announcing various high-level switches in his administration in the days leading up to Christmas. In one of the most significant changes, chief of staff Karen DuBois-Walton will become the deputy director of the New Haven Housing Authority, Slap confirmed Monday.

His former deputy chief of staff, Pierette Silverman, said she will head the city’s Youth Initiative. Silverman said she plans to solicit DeStefano’s opinion on how best to engage city youth in the actual creation and implementation of programs, which she said has not always been the case in the past.

“My goal is to really create an environment where programs and policies are implemented, where the city takes the leadership to meet the goals and the needs of our young people,” she said. “Part of what I hope to do is to create a youth-friendly city … I really feel strongly that youth have to be at the decision-making table.”

Those who want to end DeStefano’s decision-making power may run into difficulties at the upper echelons of the New Haven political apparatus. While at a College Democrats panel on Monday, Carl Goldfield, president of the Board of Aldermen, said he will support DeStefano next year. He said Greene would be an unwise choice for voters.

“I think Willie Greene’s record of accomplishment speaks for itself,” he said, but chose not to elaborate.

Greene has not yet formed an official committee to run his campaign, but will have to at a later stage. He told the New Haven Register that he believes the city deserves “real” leadership and that he resented DeStefano’s decision to run for governor while still serving as mayor.

Ward 21 Alderwoman Katrina Jones, whom Greene narrowly defeated in the recent race for Newhallville town committee co-chair, said she could only say that Greene had the right to run.

“I really didn’t have any reaction per se, outside of, ‘Well, he’s well within his right as any other registered citizen in New Haven to run for mayor,’ it’s the democratic thing to do,” she said, adding, “But no one’s come to me seeking change. I think things are running well the way they are.”

Candidates said they plan to make use of the new Democracy Fund public financing, made available by the state to mayoral candidates in New Haven who receive at least 200 donations of 30 dollars or less.