BOSTON—Matt Leduc is a registered Independent. Sitting on his front stoop while awaiting a ride to the Patriots tailgate, Leduc, like many in South Boston, said he leans Democratic but votes both ways. In the hotly contested U.S. Senate race between Elizabeth Warren and Scott Brown, that meant supporting Brown.

“I’m pretty much in the middle,” Leduc said. “I think Warren is a little bit out there. Scott Brown is a very moderate guy.”

The heart of Boston’s blue-collar backbone, Southie has become a political bellwether for statewide races. While the rest of the city is generally a Democratic stronghold, the neighborhood is home to conservative Democrats who are comfortable backing Republicans, a key swing demographic for Republicans hoping to win in left-leaning Massachusetts.

Brown won South Boston with 56 percent of the vote in 2010 and eked out victory here two weeks ago with 51 percent of the vote, but it was Warren, a professor at Harvard Law School, who ultimately took the seat.

On a recent Sunday morning, a few tired campaign posters in shop windows along East Broadway and bumper stickers askew on the backs of cars still pointed to the political split that divides the neighborhood. Voters, weary from a long election season, repeated the same sentiments over and over again.

“I like Scott Brown a lot because I think he would vote both sides. He’s very independent,” said Mary Kelly Burke.

The politically independent neighborhood became something of a touchstone for Brown’s time in Washington and his subsequent campaign. He made South Boston home to his campaign headquarters for his re-election bid and often canvassed the streets here, dressed in a Bruins jersey and jeans.

Warren, a high-powered academic with working-class roots, tried to make inroads in South Boston as well. As she began her campaign at the nearby Broadway MBTA station on a September morning more than a year ago, political pundits said Warren would need to win back swing populations like South Boston who had backed Brown in 2010 if she wanted to win.

Identifying herself as a Democrat, Burke said the days when House leader Tip O’Neill could help foster compromise are over and Washington needs to reinvent itself in a new bi-partisan fashion.

“If it was any other race, I probably would have voted for her,” Burke said of Warren, but as things stand, she said Brown would have been the best man for the job.

John Gregori agreed that Washington needs to be more flexible, but so must voters. He voted for Warren this time around, but said it’s not as simple as voting a party ticket any more.

“She seems like she’s more for the people,” Gregori said. “I come from a low-income area and it just seems like Scott Brown is for all the big money.”

Brown’s fate in South Boston points to the problems that dogged his campaign statewide and ultimately led to his defeat, said David Luberoff, a senior project advisor for the Radcliffe Institute’s Boston Area Research Initiative.

Though he was able to hold onto his Republican and Independent base, Brown failed to expand support among other groups in an election that saw much higher turnout and a stronger opponent than he faced in 2010.

“Basically they held Brown to a narrow victory in South Boston and rolled him over him in other parts of the city. And that’s a winning strategy,” Luberoff said. “He kind of held onto a base, but he wasn’t able to grow it in a significant way. This is the story of the Brown campaign.”

The morning after her election night victory party, Warren affirmed South Boston’s status as a key swing demographic, stopping by the Broadway MBTA station nearby to thank supporters living in the one Boston neighborhood she did not take.

But though ballots have been cast, South Boston’s endorsement has yet to be settled.

From his porch on East 5th Street, many blocks away from Broadway station, William surveyed the street below. William, who declined to give his last name, said he voted for Warren, but isn’t sure who the right candidate is.

“I’m still undecided,” William said, “and I voted.”

—Staff writer Nicholas P. Fandos can be reached at nicholasfandos@college.harvard.edu.