Sonia Chang-Diaz, who prevailed in her primary challenge of incumbent State Senator Dianne Wilkerson on Tuesday, is greeted at her Jamaica Plain victory party by supporter and mentor Barbara Lee. Photo by Bijoyeta Das.

By a narrow margin, voters in the Second Suffolk district on Tuesday handed the seat of incumbent state Sen. Dianne Wilkerson to her challenger, Sonia Chang-Diaz, who is now heavily favored to win the Senate seat in November.

According to unofficial results, Chang-Diaz won by some 228 votes out of 17,900 cast across the 73-precinct senatorial district, which includes parts of Dorchester and Mattapan, Roxbury, the South End, Back Bay, Jamaica Plain, and Chinatown.

"This was a hard fought campaign on both sides," a jubilant Sonia Change-Diaz said during her victory celebration at The Alchemist, a restaurant in Jamaica Plain. "We asked voters to look beyond endorsements, institutional support and make up their own minds, and they did."

Chang-Diaz's campaign manager, Deborah Shah, said that the campaign was never over-confident, despite their own internal polls that showed Chang-Diaz with a commanding lead just two weeks ago.

"The other side was well-staffed, well-armed, so were we. We stuck to our plans and at the end won."

At Wilkerson's moribund gathering inside a Massachusetts Avenue waffle and chicken restaurant, some volunteers grumbled that the incumbent was hurt by the relocation of ten polling places within the district. The shift, some argued, disproportionately impacted Wilkerson's base in Roxbury and Dorchester and left some voters confused.

Wilkerson, however, seemed more resigned to the hard reality of the night's returns than poised to mount a fight.

"This is how the process works," a relaxed-looking Wilkerson told her a 100-strong crowd of supporters at the Hen House Wings and Waffles. "We could not keep up with the reality of those nine changed precincts," she said, standing on a milk carton, as supporters switched off the flat-screen televisions tuned to FOX25 bearing the margin: 51 to 49 percent.

"I'm going to finish what I started by the end of the year, to the extent I can do that," she said, referring to bills on the controversial practice of transliterating ballots into Vietnamese and Chinese characters and other bills that she said were "sitting" in the House.

Wilkerson said she had not seen the final numbers and batted back questions from reporters on a recount or whether she would try to run as an independent on the November ballot.

"I don't know if there's even a legal basis for that," she said. "It's one idea, but it's not mine."

"I'm not looking to do a repeat of 2006," she said, referring to the first match-up she had with Chang-Diaz. In that election, Chang-Diaz came close to knocking out Wilkerson, who had failed to gather enough signatures to get on the ballot.

"After the last time they ran, you know it was going to be difficult" for Wilkerson, said Paul Watanabe, a political science professor at UMass-Boston.

Wilkerson supporters, who milled around the restaurant in a malaise while waiting for Wilkerson to arrive, pointed to the moving of polling places as a determining factor.

"I think the changing of the polling places really had some impact," said Sarah Ann Shaw, a Wilkerson campaign volunteer. "Some people went to the old polling places."

Councillor at-Large John Connolly, who attended Wilkerson's post-primary party, said he needed a closer look at the numbers, but said the November presidential election could have been a factor, despite the "cranked up" organization that Wilkerson had.

"There's always an underlying fear that people are focused on November and this election was off the radar," Connolly said.

Wilkerson has held the Second Suffolk district seat, which includes much of Ward 14 in Dorchester and Mattapan, since 1993. She is the Senate chair of the State Administration and Regulatory Oversight Committee.

Chang-Diaz has worked at the Massachusetts Budget and Policy Center and as an aide to former state Sen. Cheryl Jacques. The daughter of an astronaut, she has also worked as a public school teacher.

A series of several debates held over the summer highlighted how little difference there was between them on policy. Both come down on the left or progressive side of most issues. Chang-Diaz based her candidacy mainly on a theme of ethical and responsible leadership, noting Wilkerson's campaign finance problems, which were underscored by an August announcement of a settlement between Wilkerson and the state attorney general's office. The agreement has Wilkerson paying $10,000 for violating multiple campaign finance laws.

Still, Wilkerson had the endorsements of Gov. Deval Patrick, who made auto-calls on her behalf to 20,000 numbers, and Mayor Thomas Menino, whose powerful political machine was active for Wilkerson on the ground in recent weeks.

Chang-Diaz racked up her own endorsements, including ones from the Boston Globe, the Boston Herald, and most surprisingly, Bay Windows, the region's largest gay and lesbian newspaper. In their endorsement of Chang-Diaz, the newspaper broke with several GLBT political groups who had backed Wilkerson, citing her record on gay rights, including her pushing for the repeal of the 1913 law employed to prevent out-of-state gay couples from marrying.

Allies said that Wilkerson will likely have little trouble landing on her feet.

"She is obviously very, very talented," said Councillor Charles Yancey. "If anything, this may lift a burden from her shoulders so she can pursue other things."

Chang-Diaz's admirers expect big things from the woman who will be Senator.

"She is an incredibly hard worker, dedicated to public service and is willing to go the extra mile," said Barbara Lee, founder of a foundation that supports female candidates and one of Chang-Diaz's mentors. "I told her she is a superstar."

Chang-Diaz will face one opponent - William Theodore Leonard, representing the Socialist Workers party - in the November 4th final election.
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Incumbent state representatives Marie St. Fleur and Willie Mae Allen each trounced their opponents in Tuesday's primary election and will run un-opposed in November's final. St. Fleur bested Roy Owens, 1,443 to 710. Willie Mae Allen defeated Faustina K. Gabriel, 1,951 to 603.