... In Sanders’s office in the Dirksen Senate Office Building one day this past summer, the Brooklyn accent is very much in evidence. Another Sanders trademark, not so much. Mark Leibovich wrote in the New York Times Magazine in 2007, after Sanders beat his Republican opponent for senator by 33 points, “Journalistic convention in Vermont mandates that every Sanders story remark on his unruly hair as early on as possible. It also stipulates that every piece of his clothing be described as ‘rumpled.’”

He’s not as rumpled now. He’s a potential presidential candidate who was at the white-hot center of one of the most intense political issues of the summer: the scandal of the Department of Veterans Affairs falsifying records involving long waiting periods for care. The week I visited, Sanders had just passed a bipartisan bill he wrote with Republican senator John McCain to fix the broken federal agency. It allows veterans to opt out of VA care and receive private care if they’ve had long delays or live more than 40 miles from a VA facility; makes it easier to remove incompetent VA officials; and authorizes the construction of 26 new VA facilities in 17 states and Puerto Rico. The bill proved a rare nostalgic glimpse of the Washington of yesteryear, when Democrats and Republicans actually worked together to solve real problems.

It also shows how Sanders has transformed himself. He’s introduced a Restore Our Privacy Act to curtail the surveillance provisions of the Patriot Act and a Comprehensive Dental Reform Act to address woeful access to dental care; helped write the first new surface transportation bill since 2005; and, as founder of the Senate’s Defending Social Security Caucus, introduced legislation to keep its trust fund solvent for another 75 years. Yes, he’s still Capitol Hill’s socialist gadfly. But he’s also become a player.

Befitting that role, his suit is veritably crisp. (Last time I visited him, in his House office in 1998, he was wearing a ratty blue sweater.) And at his talk at the Institute of Politics, he connected so skillfully with his audience—first asking every questioner’s name, then addressing them by those names with eye contact—that, waiting to see him in his office, I compliment his staff on the strides their boss has made in dialing down his famous irascibility. They beam with an almost filial pride.

Although, I discover once we begin the interview, he hasn’t changed in one respect: he’s still frustratingly irascible in the presence of journalistic profilers. He hates talking about himself. He thinks it’s a distraction from what journalism should be about: serious issues, not, as he puts it, gossip. Most of his sentences in response to my questions on his College career devolve into incomprehensible mumbles. He looks at his watch. He gazes imploringly at his press secretary. (“We’ve got a vote at what time, 5:30?”)

On the subject of his college career, one of his mumbles follows the words “kids of doctors and lawyers.” His father sold paint. He felt out of place. Politics helped. Remembers Parker, “The people who were politically active were sort of drawn together, because we were such a small number.” And by Sanders’s first winter quarter, political activity on campus intensified considerably. The student chapter of the NAACP had decided to disband and reform themselves as a student chapter of the more militant Congress of Racial Equality (CORE)....