Just a month ago, political pundits were giving Cabral long odds on her bid to keep the sheriff’s office.

In debates Cabral spoke about the reforms she had brought to the ailing Suffolk County jails, acknowledging that she had incurred the wrath of many in the corrections officers’ unions. While politics in Boston have traditionally hinged on ethnicity and geography with ideas as a distant third, Cabral’s message of reform may have struck a chord in this election, according to veteran political activist Ron Marlow.

“I think her message of professional management resonated with voters in a way that conventional pundits missed,” Marlow said. “I don’t think you’ll find anyone who could have predicted the tidal wave by which she won in the end.”

Early on Cabral’s campaign had little presence in the black community that many saw as her electoral base. And because voters of color are notoriously absent in preliminary elections, many scoffed at the idea of a groundswell of support for Cabral.

Cabral’s campaign strategy seemed to be focused on the high-voting predominantly white wards — South Boston, West Roxbury, Hyde Park — that Murphy and other Irish Catholic politicians have relied on for decades.

Few believed Cabral could beat challenger Stephen Murphy on his home turf.

While Cabral was able to wrest Hyde Park from Murphy with an impressive 60 percent of the votes in Ward 18, he did manage to keep his grip on South Boston’s wards 6 and 7, Charlestown’s Ward 2, Ward 1 in East Boston, West Roxbury’s Ward 20 and Ward 16, which comprises the high-voting and predominantly white Neponset section of Dorchester.

Although Murphy won those wards, Cabral was able to penetrate deep into those areas, losing West Roxbury to Murphy by just 76 votes.

The wards Murphy won constitute the high-voting donut that surrounds the traditionally low-voting communities of color at the geographical center of the city — Roxbury, Dorchester, Mattapan, Jamaica Plain and the South End.

Yet in this preliminary, the hole in the donut was filled.

“This is the highest primary turnout we’ve seen in the black community since 1983,” noted City Councilor Chuck Turner, referring to Mel King’s successful bid for a slot on the mayoral ballot two decades ago.

While a strong get-out-the-vote effort was mounted by a coalition of community-based organizations (see story, page 3), an organization of black community political activists took control of Cabral’s communities of color campaign in the last weeks of August, drumming up a groundswell of support in her base.

“We had four weeks to inform communities of color about her campaign and educate them on the differences between her and Murphy,” said Mukiya Baker-Gomez, who led Cabral’s campaign in communities of color. “If her base hadn’t turned out, she would have lost.”

Focusing on wards 8-15, 17 and 18’s precincts 1-6 and 21, Baker-Gomez mobilized an army of more than 100 volunteers including seasoned political activists who zeroed in on both frequent voters and newly-registered voters. The activists used phone-banking to identify Cabral supporters, then asked those supporters to spread the word about the primary.

“We won every single precinct in communities of color,” Cabral said. “We significantly outdistanced the number of votes Murphy got.”

While Cabral was able to garner 31 percent of the votes in South Boston’s wards 6 and 7, Murphy came away from Roxbury and Dorchester’s wards 12 and 14 with less than 8 percent of the vote. Cabral’s base held.

While Murphy was able to secure endorsements from a number of African American activists, none of them delivered. The endorsement from the Rev. Eugene Rivers, which garnered a news story and photograph in the Boston Herald, netted Murphy just 9 votes in Ward 17’s Precinct 1, where Rivers’ Ella J. Baker house is located. Cabral received 127 votes in that precinct.

Cabral’s community of color operation dropped 30,000 pieces of literature informing voters of the election, including a mailing to more than 10,000 newly-registered voters.

Cabral’s campaign also received a boost from other elected officials of color representing Boston, all of whom gave endorsements. Elected officials then covered polling stations, urging voters to cast their ballots for Cabral.

Cabral’s victory should dispel any doubts about the strength of the vote in communities of color, according to Turner. While some political observers may have seen Felix Arroyo’s second-place finish in the at-large race as a unique event, Turner says Cabral’s victory demonstrates the power of the vote in the black, Latino and Asian communities.

“I think it really suggests there’s a new day where black, Latino and Asian voters are coming out in greater numbers,” he commented. “It challenges black and Latino elected officials to work harder. Our community is looking for victories. We have to work together.”