WASHINGTON —

When President Obama cut a deal with congressional Republicans in December 2010 to extend tax cuts for the wealthy, Sen. Bernard Sanders, the brusque Vermont independent who calls himself a socialist, decided it was time for a protest.

He had a cup of coffee and a bowl of oatmeal in a Senate cafeteria, marched into the chamber and began talking. He talked for so long — railing for 8 hours, 37 minutes about economic justice, the decline of the middle class and “reckless, uncontrollable” corporate greed — that his legs cramped. So many people watched online that the Senate video server crashed.

Today the issue of tax cuts for the wealthy is once again front and center in Washington, as part of the debate over how to reduce the federal deficit. And Sanders is once again talking, carving out a place for himself as the antithesis of the tea party and becoming a thorn in the side to some Democrats and Obama, who he fears will cut Social Security, Medicare and Medicaid benefits as part of a deficit-reduction deal.

A number of congressional Democrats agree with Sanders that “no deal is better than a bad deal,” but he may be the most vocal.

He is emboldened by his recent re-election with more than 70 percent of the vote — “Seventy-one percent, but who’s counting?” Sanders said — and he appears to be making a little headway. Sanders has been pressing Obama to take Social Security off the negotiating table, and the administration now says changes to the retirement program should be considered on a “separate track” from a deficit deal.

“I think maybe he has learned something,” Sanders, 71, said of the president. “After four years he has gotten the clue that you can’t negotiate with yourself, you can’t come up with a modest agreement and hope the Republicans say, ‘That’s fair, you’re OK, we’ll accept that.’ He’s reached out his hand, and they’ve cut him off at the wrist.”

The Senate is a polite place, so Republicans have little to say about their colleague from Vermont with the thick Brooklyn accent.

After four years of accusing Obama of practicing “European-style socialism,” Republicans are not enamored of a man who embraces European-style socialism, and who carries a brass key chain from the presidential campaign of Eugene Debs, who ran in the early 1900s as the Socialist Party candidate.

“Bernie?” Sen. John Cornyn, R-Texas, said with a raised eyebrow and a sly smile. “He’s one of a kind.”

Vermont Republicans are a bit more pointed. Richard Tarrant, a businessman who ran against Sanders in 2006 and was trounced, agrees with him that taxes should rise for the rich. But he sees his former opponent as a populist “advocating class warfare” and raising “false hope” about programs that are unsustainable.

Sanders, who has a habit of answering questions with questions, says it is Republicans who are engaging in class warfare.

“Do we really say we’re going to balance the budget on making major cuts in disability benefits for veterans who have lost their arms and legs defending America while we continue to give tax breaks to billionaires?” he thundered, without pausing for breath. “Is that what the American people want? They surely do not, and only within a Beltway surrounded by Wall Street and big-money interests could anyone think that is vaguely sensible.”

Sanders, who Wednesday was appointed chairman of the Veterans Affairs Committee, has 28 of the Senate’s 51 Democrats with him on keeping Social Security out of the deficit talks; all signed a letter that he and the Senate Democratic leader, Harry Reid, sent to the president. In the House, 104 Democrats — more than half of the caucus — signed a similar appeal. And 13 Senate Democrats, plus Sanders, signed a second letter demanding that entitlement programs be spared “harmful cuts.”

To Sanders, “harmful cuts” means any cuts in benefits. He says that entitlement spending should be trimmed only by wringing out inefficiencies. Many budget experts say that is unlikely to produce as much savings as Obama and the GOP want.

But Sen. Tom Harkin, D-Iowa, believes Sanders has some silent support.

“I think Sen. Sanders represents the majority of our caucus,” Harkin said. “Not all of it, but the majority. They may not be saying it in the same way that Sanders says it, not as aggressively as Sen. Sanders. But I think that’s where they are.”

With his gruff exterior and utter lack of interest in the false pleasantries of politics, Sanders is an unlikely figure to have gained admittance to the Senate.

He is a onetime college radical who led a sit-in in 1962 at the University of Chicago to protest discriminatory housing policies. Before becoming successful in politics, he knocked around from job to job: carpenter, tax clerk, writer.

He took his first trip to Vermont in the mid-1960s, after picking up a tourist brochure at Rockefeller Center. He and his wife at the time bought 85 acres of woodlands for $2,500 and began spending summers in a “sugar cabin” — a shack where maple syrup is made — without electricity or indoor plumbing. In 1968, they moved permanently.

In 1971, he ran for the Senate in a special election on an anti-war platform and got 2 percent of the vote. Ten years later, he squeaked past a six-term Democratic incumbent to become the mayor of Burlington, winning by 10 votes.

In a small state like Vermont (population 626,000), Sanders has proved to be a master of retail politics. This year, he held dozens of town meetings and won without running a single TV ad.

“Bernie engages everyone,” said Garrison Nelson, a political scientist at the University of Vermont. “He walks the streets of Burlington alone, without an entourage. People will come up to him and say, ‘You lousy communist SOB,’ and he’ll say: ‘What do you mean? Clarify yourself.’”

If Sanders could have his way, the United States would be like Finland or Sweden, where the government guarantees child care and health care. His philosophy flows from his Brooklyn boyhood; he grew up the son of a paint salesman, in a home, he said, where “money was always a source of friction.”

The family lived in a one-bedroom apartment; the young Sanders slept in the living room with his older brother. His mother, who died at 46, dreamed of owning a “private house.” His father, a Polish immigrant, reminded him of Willy Loman, the character in “Death of a Salesman,” who is fired after 34 years with the same company.

The play offers a lesson that the senator says is too often forgotten in Washington, “of people who have money not understanding what it’s like not to have money.”

Sanders intends to make people understand, and if he thinks it is necessary to stand on the Senate floor for another 8 hours, 37 minutes, he just might do it.