The Vermont Senator Bernie Sanders is a genuine economic populist, but not an attack dog. PHOTOGRAPH BY ANDREW HARRER/BLOOMBERG VIA GETTY

If you were expecting a slick campaign video, or a big set-piece speech, to herald Bernie Sanders’s entry into the 2016 race, you don’t know the man or what he represents. For months now, the seventy-three-year-old Vermont senator has been indicating he would run for President. The official announcement, which came in the form of an e-mail to his supporters, merely confirmed that he’ll contest the Democratic primary rather than run as an independent. (Although he caucuses with the Senate Democrats, Sanders was elected in 2006 and 2012 as an “independent socialist.”)

The contrast with the carefully orchestrated launches of the Clinton, Cruz, and Rubio campaigns, to name but three, wasn’t due to the fact that Sanders hasn’t got any money—he has almost five million dollars left over from his last Senate campaign. Sanders was sending the message that he isn’t so much a candidate as an anti-candidate. Even more than Howard Dean’s pitch, in 2004, Sanders’s will be based on the proposition that American politics are broken and corrupted to their core, and that only an insurgency can do anything about it. “Let’s be clear,” Sanders said in his e-mail. “This campaign is not about Bernie Sanders. It’s about a grassroots movement of Americans standing up and saying: ‘Enough is enough. This country and our government belong to all of us, not just a handful of billionaires.’ ”

That last line is one Sanders uses a lot, and it cuts across party lines. Mainly, he uses it to lambaste post-Citizens United Republicans, with their motley assortment of right-wing sugar daddies, from the Koch brothers to Sheldon Adelson to Harold Simmons. But Sanders has also accused the Democratic Party of playing the money game and pandering to wealthy donors. Last November, for example, he said that Party leaders had failed to make clear “that they are prepared to stand with the working-class people of this country, take on the big-money interests.” Now that he’s running in the Democratic primary, we can expect to hear him repeat this argument and apply it to the establishment candidate, Hillary Clinton. Indeed, he’s already doing this.

Asked by Jonathan Karl, of ABC News, what he thought about the controversy over donations from wealthy foreign interests to the Clinton Foundation, Sanders replied, “It tells me what is a very serious problem. It’s not just about Hillary Clinton or Bill Clinton. It is about a political system today that is dominated by big money. It’s about the Koch brothers being prepared to spend nine hundred million dollars in the coming election. ... We’re looking at a system where our democracy is being owned by a handful of billionaires.”

Sanders isn’t an attack dog. He likes to boast that he has never run a negative ad, and, rather than personalizing things, he generally sticks to the issues. Asked at a press conference outside the U.S. Capitol on Thursday why he was a better candidate than Clinton, he dodged the question. But the Clinton Foundation isn’t the only area where, in the past few days, he has raised questions about Clinton’s record. During an interview on CNN, he said that she ought to say whether she supports the Trans-Pacific Partnership, a free-trade deal that the Obama Administration is trying to complete. And, in an interview with the Associated Press, Sanders reminded people that Clinton voted for the Iraq War and he voted against it.

Despite these pointed statements, the conventional wisdom in political circles is that Sanders’s entry into the race is good news for Team Brooklyn. He can’t win the primary, the argument goes, and he will occupy the space to the left of Clinton, thus denying it to more plausible candidates, such as Martin O’Malley, the former governor of Maryland. That may be true. But if Sanders succeeds in building a vigorous grassroots campaign, as Dean did in 2004, he could still have a significant impact on the contest.

Admittedly, that’s a big if. For much of his career, Sanders has been a loner rather than a team player. His social-media presence is respectable but not huge. (His Facebook page has just under a million “likes”; on Twitter, he has close to three hundred thousand followers. ) Until he shows that he can attract big crowds and raise money from small donors, other players on the progressive wing of the Democratic Party, such as labor unions and environmental groups, will remain wary of endorsing him.

But, for all the challenges Sanders faces, his presence in the Democratic primary field is surely a plus. As I pointed out a few months ago, when he released his Economic Agenda for America, he’s a genuine economic populist, and many of his policy proposals—such as spending a trillion dollars on infrastructure investment, introducing a carbon tax, and replacing private health insurance with Medicare for all—are eminently defensible, if politically unrealistic. Most of all, he will provide a voice to those Democrats who agree with him that the U.S. political system has been bought, lock, stock, and barrel. In the televised debates and elsewhere, he will demand that the other candidates, Clinton included, respond to this indictment and say what they intend to do about it.

That alone is sufficient reason to welcome Sanders to the race. If, in addition, he manages to expand the range of policy options that can be openly discussed and forces Clinton to move from generalities to specifics, he will have performed a real public service.