Democratic leaders in Massachusetts and Washington are convinced the Oklahoma native is the best chance the party has to recapture Edward M. Kennedy’s Senate seat. She has spent the last month speaking with small invitation-only groups of Democrats, generating excitement within the party’s rank-and-file.

“It’s about being willing to take a good idea and fight for it,’’ she said later. “It’s being willing to throw your body in front of a bus to block bad ideas.’’

“There are some things worth fighting for and right now it’s about fighting for the middle class,’’ she said more than once.

She now talks as someone who has been to Washington, seen its dysfunction firsthand, and come away wanting to reform it. While Brown emphasizes crossing the aisle to find compromise, she talks about fighting. And she does it without apology.

Warren, 62, has returned to Massachusetts after a stint in Washington where she led a panel that monitored the banking bailout and then established the new federal Consumer Financial Protection Bureau at President Obama’s behest. Both jobs put her at odds with Republicans who said she was too hostile toward business to effectively lead the agency and ultimately, Obama declined to nominate her.

In an interview yesterday, the Harvard Law School professor did nothing to dispel the assumption that she plans to run, answering detailed questions about the economic issues she would emphasize in her campaign and the patchwork details of her personal story.

Warren is the would-be Senate candidate who has yet to declare her intentions, but has made enough moves in the race that nearly everyone who is watching closely sees her as the biggest name in a Democratic field attempting to defeat Republican Scott Brown next year.

“I scratched it out,’’ she added, leaking just a hint of her Oklahoma accent. “I took care of myself. I took care of my family.’’

“There’s nothing to handle. It is what it is. I’m also 5 foot 8,’’ she said, holding her gaze on the questioner. “Yeah, I’m a Harvard professor. But I wasn’t born at Harvard. I came up scrappy. I came up the hard way.’’

And when she’s asked how she’ll handle the chief knock against her, that she’s a Harvard elitist - an image that Republicans are already trying to tag her with - her answer is direct.

Repeatedly, she declares that middle-class families don’t have a lobbyist in Washington, while the bankers have enough of them to pack a senator’s waiting room. It sounds like the beginnings of her stump speech.

Elizabeth Warren has been in full live-wire mode for 45 minutes, joking about her grandchildren, pounding the table as she dissects the mortgage crisis, insisting she will not temper her two-fisted style if she runs for US Senate.

But she has yet to face any voters outside that circle, including the independents and conservative Democrats who helped elect Brown in last year’s special election. Her success, if she runs, will depend in great part on her ability to blunt the GOP attacks on her Harvard and Washington ties and to sell herself as a populist fighting for their interests.

To do that, she’ll have to convince voters that her personal story is as much a part of her character as her Ivy-League credentials.

In an hourlong interview, she spoke often of the now-familiar story of her humble roots in Oklahoma. Her parents struggled financially, almost losing their home after her father had a heart attack. But it was also a time, she said, when the government made it possible for a woman who married at 19 and dropped out of college to get an education that led her to the Harvard Law School faculty in 1992.

“I came out of a hard-working middle class family,’’ she said. “I lived in a America that created opportunities for kids like me.’’

“I now see an America in which our government works for those who already have money and already have power,’’ she said.

Warren staked out traditional liberal Democratic positions on several big issues: She supports abortion rights, gun control, and gay marriage, but she opposes casinos, even as her political consultant is a lobbyist, Doug Rubin, working on behalf of a major gambling enterprise. She defended her hiring of Rubin, saying it was a practical decision because of his history of managing successful campaigns, most notably his work for Deval Patrick.

But she declined to offer specifics on where she differs with Brown or Obama. Nor would she say when she will decide whether she will run, only saying she will make up her mind after Labor Day. She has committed to teaching two classes at Harvard for the fall semester.

Warren made it clear that any campaign she launches will focus primarily on economic issues, particularly the theme that America has shifted from policies designed to promote and nurture middle class families to ones that promote the interests of the powerful and rich. It is a drumbeat Warren has sounded for more than a decade, in her writing and in her public appearances.

She talked with pride yesterday of how she walked the halls of Congress, knocking on lawmakers’ doors trying to sell them on the idea of creating a powerful consumer credit agency that would toughen the laws regulating the country’s financial institution. “I would walk out of a senator’s office and the office would be completely jammed with lobbyists who were there to explain why the consumer agency was bad,’’ she said. “There was not enough room for them to sit down.’’

In the end she won passage. With Obama’s support and Brown’s critical vote, the agency was created as part of the Dodd Frank Wall Street Reform Bill.

As Warren now focuses her energy on whether to run, she looks toward a crowded Democratic field.

Already in the race are: Setti Warren, the mayor of Newton; Alan Khazei, cofounder of City Year; state Representative Thomas P. Conroy; Bob Massie, the 1994 nominee for lieutenant governor; Herb Robinson, a Newton engineer; and Marisa DeFranco, a North Shore attorney.

Warren, though, has her sights on Brown. She said she has only met the senator once, while in Washington. It was a chance encounter when they were both invited to a dinner at a private home this spring. By her account, it wasn’t a very remarkable meeting. She said she and Brown spent little time chatting.

“It was a cast of thousands,’’ she said. “It was hello.’’

Noah Bierman can be reached at nbierman@globe.com. Follow him on Twitter @noahbierman. Frank Phillips can be reached at phillips@globe.com.

© Copyright 2011 Globe Newspaper Company.