Voters check in at Union Temple Baptist Church in Southeast Washington D.C. on Tuesday. (Jared Soares/For The Washington Post)

Three times in the past three years, candidates in citywide District races have tried to assemble a winning coalition by linking the city’s traditionally white wards with residents of fast-growing ­areas elsewhere. Three times, they failed.

On Tuesday, a candidate finally broke through. But observers are split on whether David Grosso’s victory over D.C. Council incumbent Michael A. Brown reflected a sea change in the city electorate or merely Brown’s dismal political and personal circumstances.

Tuesday’s map looked much as it did in the 2010 mayoral primary, the 2011 at-large D.C. Council special election and this year’s Democratic at-large primary: A drastic east-west split, with majority-black wards to the east tilting heavily one way and majority-white wards tilting the other.

But unlike Vincent C. Gray and Vincent B. Orange before him, Brown could not rack up sufficient margins in largely African American wards 5, 7 and 8 to offset Grosso’s overwhelming strength in wards 1, 2, 3 and 6. Most devastating to Brown was the collapse of support in his home Ward 4, where Grosso built a narrow lead.

“If your ward doesn’t give you some home cooking, who . . . is going to feed you?” said Bob King, a veteran community activist in the Fort Lincoln neighborhood of Northeast. “Michael Brown’s ward didn’t feed him.”

A decade ago, King said, African American votes in Ward 4, in the city’s northern corner, as well as in wards 5 and 6, areas along the west bank of the Anacostia River, might have saved Brown.

But the city is now larger, younger and whiter. And in the current, ethically sensitive po­litical environment, King said, Brown was a “dead man walking” because of personal foibles that included late tax payments, a oft-suspended driver’s license and missing campaign money.

“I cannot take a candidate on my back,” said King, who organized buses to get voters to the polls on Brown’s behalf. “You cannot win without the seniors, but, at the same, the seniors cannot be the sole factor.”

The city’s center of political gravity appears to have shifted southward. Traditionally, upper-Northwest wards 3 and 4 have led city vote totals. But, thanks to both population growth and redistricting, the most at-large ballots Tuesday were cast in Ward 6, which stretches between the Capitol and the Anacostia.

Chuck Burger, a Capitol Hill real estate agent and political activist, said the huge vote totals for Grosso there showed that the ward is “coming of age politically.”

“We are the big kid on the block here,” Burger said. “The demographics have changed and the voting rolls have swelled, and they have turned into a more activist voter. It used to be [wards] 3 and 4, but now it’s 3, 4 and 6.”

Burger said Grosso benefited from his ties to former Ward 6 council member Sharon Am­brose, for whom he worked, as well as from the endorsement he received from the ward’s popular council member, Tommy Wells (D). But he added that Grosso also campaigned heavily in the neighborhood.

“As far as they were concerned, Grosso worked hard, appeared to be smart and wasn’t Brown,” Burger said.

In an interview, Grosso said he prevailed by getting his reform message in front of tens of thousands of voters. “I was able to reach a lot of people and when they saw me, they recognized me as the candidate with the message of good government,” Grosso said.

But Grosso was hesitant to describe his victory as representing a major shift in District politics. Instead, he said he’s “at the forefront” of a debate that will likely accelerate next spring during the special election for the at-large seat left vacant by the election of Phil Mendelson (D) as chairman. Grosso said he hopes to play an active role in that election and said he will probably endorse one of the contenders.

That election may prove a bigger test of whether city voting power has shifted permanently. The at-large race was complicated not only by Brown’s tarnished image and weak campaign, but also in that it was a battle of independents in a majority-Democrat city. (Orange, the Democratic candidate, won reelection to the other at-large seat handily, outpolling Grosso in six of eight wards.)

A Democratic primary — which excludes tens of thousands of independent, Republican and other-party voters — would likely have been a tougher one-on-one challenge for Grosso, who, like Brown, is a former Democrat. And it’s possible that the center of political gravity might shift back in future, nonpresidential election cycles.

Burger noted that growing numbers of Ward 6 residents live in new condominiums or apartments near Nationals Park and in NoMa — pockets of newcomers with little history of voting in off-year local races.

“Every year isn’t a presidential race, and a sea change only happens when you push the wave along,” Burger said. “But it shows there is a base there that can be engaged and can be worked with and can grow.”

In any case, a candidate’s appeal in Ward 4 — the turnout leader in most local elections in the past decade — will remain pivotal, as it did Tuesday.

Muriel Bowser, the ward’s Democratic council member, said she was “not entirely surprised” with Tuesday’s result, based on the conversations she’d had with voters in her ward, not because of demographic shifts.

To assume those shifts were responsible for Brown’s loss, she said, “you would be assuming . . . that only people who moved to the ward recently were voting for [Grosso], and I don’t know that would be the case.”

In one key precinct — encompassing the Shepherd Park and Colonial Village neighborhoods, a multiracial, high-turnout area rich in civic-minded residents — Brown won about 400 fewer votes than in 2008 and was narrowly outpolled by Grosso.

“Michael grew up in that precinct,” she said. “That’s tough.”