WASHINGTON — First came the big crowds, now comes the big money. At this point, anyone who doesn’t take Bernie Sanders seriously must not be paying attention.

Sanders’ campaign announced that it raised an eye-bugging $26 million in the third quarter — essentially matching the $28 million raised during those three months by Hillary Clinton, long considered the presumptive Democratic nominee. If that doesn’t make Clintonistas nervous, they need defibrillation.

On paper, Sanders is wildly unlikely as a Democratic nominee. He’s hardly even a Democrat — he represents Vermont in the Senate as an independent. He proudly describes himself as a socialist, hanging around his own neck a label that is supposed to be fatal in American politics. And he’s 74, making him the eldest among the Democrats’ gerontocratic field.

Yet polls show Sanders leading Clinton in New Hampshire and essentially tied with her in Iowa. It is possible that Clinton could lose the first two primary states and still win the nomination, but only two Democrats have accomplished this feat — Bill Clinton, who didn’t even campaign in Iowa in 1992, and George McGovern, for whom the subsequent 1972 general election did not work out well.

Sanders’ money haul has to worry Clinton, not just for its size but for the way it was achieved. The vast majority came in small donations — Sanders’ average contribution is less than $25. This means he can keep going back to these same supporters later in the campaign. Far more of Clinton’s donors, by contrast, have already maxed out their allowable contributions for the primaries.

While the Clinton machine has made a point of being thrifty — requiring many staff members, for example, to take the bus between Washington and campaign headquarters in Brooklyn — it’s still, as Donald Trump might say, yooooge. And unlike Sanders, Clinton has been paying for television ads in the early states and consultants of the kind who don’t come cheap.

As a result, even though the Clinton campaign, since inception, has raised $75 million to Sanders’ $40 million, it’s conceivable that Sanders might presently have more in the bank. He’s sitting on $25 million in cash; she won’t say how much she has.

All of which makes the Democratic race as unsettled as the GOP contest but in a different way. On the Republican side, there’s a civil war in the party between outsiders and insiders, with three nonpoliticians leading a large establishment field that turns out to be far less talented than expected. Among Democrats, the Sanders insurgency and the yearning for Vice President Joe Biden to enter the race show that the party has not embraced Clinton as the inevitable nominee. As recently as July, according to the Real Clear Politics poll average, she led Sanders nationally by 50 points; now, that lead is down to about 14.

What explains Sanders’ appeal? Much is made of his “authenticity,” and it’s certainly true that there is a refreshing lack of artifice about him. But tousled hair alone isn’t enough to explain his rock-star status in college towns and other liberal redoubts.

I believe his success to date is due to insight and ideology. Sanders was perceptive enough to frame a message that is perfect for the zeitgeist: The system is rigged to benefit the rich and powerful at the expense of everyone else. And having identified the problem, he offers clear and internally consistent remedies.

Sanders wants truly universal health care — something Clinton, too, once supported. He wants child care and family leave for all. He wants tuition to be free at every public university in the nation. He wants to expand Social Security benefits, not cut them back. He wants to raise taxes on those who can afford to pay. He wants to expand the scope of government as an instrument of the popular will and guarantor of the people’s well-being.

This clarion call arrives at a time when polls show that Americans across the political spectrum are disillusioned by politics, fed up with politicians and worried about the state of the nation.

Republicans who salivate at the thought of running a general-election campaign against a 74-year-old socialist should note that their own front-runner, Trump, also proposes initiatives that would vastly increase the power of government, such as rounding up and deporting 11 million undocumented immigrants.

I don’t think this is a coincidence. This cycle’s breakthrough candidates aren’t calling for government to leave us alone. They’re calling for it to do big, bold things.

Eugene Robinson is a Washington Post columnist.