WASHINGTON — Elizabeth Warren seems tired as she sits down in her straight back office chair at the end of a long rookie year in the Senate. But her voice suddenly rises when her favorite subject comes up, the populist ideas on which she has spent the last 30 years.
It's not just Democrats who need a jolt of it, she says, holding up her arm like a crossing guard.
"Everyone," the Massachusetts Democrat says. "Democrats, Republicans, Libertarians, vegetarians."
Warren's first year has found her in the middle of the debate over the future of both her party and the country. She has been simultaneously bold and cautious — trying to harness the zealous political activists who champion her, without upsetting those in the Senate who outrank her. With little chance of getting big laws through the Senate, Warren has tried to rattle the cages of bureaucracy and swing public opinion in her direction.
"I want to be effective and I'm trying to build partnerships, but it's about changing what goes on here,'' she said. "It's got to be.''
For her second year, Warren did not promise any tactical differences. But she said she will put a greater emphasis on two of her pet issues: lowering the cost of student loans and doubling investment in research funding. Both of those face an uphill battle in a Congress that is not only hampered by gridlock but is also increasingly concerned with lowering the size and scope of government.
She also promised to spend more time fund-raising and campaigning for Democrats in the upcoming Senate elections, saying it is crucial that her party maintain a majority so she can continue to hold banks accountable.
Even as lawmakers were preparing last week to head back home for the holidays, Warren held two news conferences. She proposed a bill to prevent employers from reviewing job applicants' credit histories, and joined in on a series of measures with Democratic Senators Richard Durbin of Illinois and John F. Reed of Rhode Island to put more money into college grants and more pressure on universities to help students get better loan packages.
Some in Washington are comparing Warren and other emerging liberals to a nascent version of the Tea Party within the Republican Party. Warren flatly rejected the comparison during an interview with the Globe in her office, where she displays a vintage bumper sticker from the late Senator Paul Wellstone, an unabashed liberal from Minnesota.
But in doing so, she made a similar argument to the one made by Tea Party lawmakers: that the American people are with her, especially when it pertains to increasing Social Security benefits.
"You're saying something political and I'm talking about something where America is," she said. "Only in the bubble of Washington is the center around how to cut Social Security."
Opinions about Warren hew strongly along ideological lines. Liberals tout her influence in pushing Democrats to speak more forcefully about economic inequality and against the influence of big banks.
They cheer her for pushing regulators to crack down, including an agreement in June by the Securities and Exchange Commission to force more financial institutions to admit wrongdoing when they settle cases. They credit her with pushing President Obama to nominate Janet Yellen as chairwoman of the Federal Reserve instead of Lawrence Summers, the former treasury secretary and Harvard president who many on the left saw as too closely aligned with Wall Street.
Some conservatives argue that she has been more about showmanship than substance and that her stature has been overblown by partisans, while some moderate Democrats have warned she is pushing her party too far to the left.
"It's a flash in the pan. I just don't see yet that she's going to be a major force," said Peter J. Wallison, a financial policy specialist at the American Enterprise Institute andformer adviser and White House counsel to President Reagan who helped deregulate the financial industry. "When everyone else is worried about the debt and the fact that entitlements are going to eat us alive and are already eating us alive, someone is going to pick up the flag for even more entitlement…I just don't see that it is going to achieve anything."
Some former critics have quieted down now that Warren is in the Senate. During last year's election, the political director of the Chamber of Commerce, Rob Engstrom, said "no other candidate in 2012 represents a greater threat to free enterprise than professor Warren." The Chamber declined to comment for this story and said its annual congressional score card would be out in March.
But Warren has worked with some Senate Republicans and has not generated the type of resentment in the chamber that Senator Ted Cruz of Texas and other Tea Party Republicans have for their more provocative tactics. She called her time working on a proposal to regulate banks with Senator John McCain, the Arizona Republican who has praised her command of the issues, "just plain ol' fun."
"My sense is that she thought some about how to present herself to her colleagues and to the country before she assumed office," said William A. Galston, a Brookings Institution scholar and former adviser to President Clinton. "My sense is that Warren has done a pretty good job of balancing the visibility she has with buckling down and doing her job as a senator."
Warren attends most of her committee meetings and stays until the end, longer than other senators. She defers to senior senators during news conferences. She limits her appearances with media and declines to comment on the issues of the day in the hallways of the Senate.
Because of her lack of seniority, she sits in the back corner of the Senate chamber, near other newly elected senators, far away from majority leader Harry Reid and his Republican counterpart, Mitch McConnell, or others who are in on the rare big deals that are made.
"There's inside power and outside power," Galston said. "She has very considerable outside power, and she's earned it. She stands for something. But transforming outside power into inside power is not so simple."
Warren seems keenly aware. She has proposed only four stand-alone bills, none of which have passed. She has worked on other lawmakers' bills as well, including a measure approved last month to better regulate compounding pharmacies. The law was passed in response to last year's deadly fungal meningitis outbreak that was linked to a Massachusetts drug maker.
But the power to push bureaucrats and shift the national conversation may be her most effective tools. She cites an example in which she proposed an amendment that would force the Federal Housing Administration to tweak its rules on loan modification so that government benefits and alimony would count as income. She said the agency changed its rules to satisfy her concern, even though the larger bill she was amending never made it out of Congress.
"There are retirees who are able to stay in their homes because of that change," she said. "There are families staying in their homes because of that change. That's a cool feeling."
Yet it's an incremental change, according to Bruce Marks, chief executive officer of Neighborhood Assistance Corporation of America, a housing advocacy group based in Boston.
"If she's saying that this is a significant impact on FHA modifications, that's not the reality on the ground," Marks said.
But, he added, "she's changed the tone in Washington."