BURLINGTON, Vt. — Senator Bernie Sanders of Vermont still flies coach to his campaign events, sometimes taking the middle seat. He has not run any commercials, instead saving his money for a news media blitz this winter in Iowa, New Hampshire and the Super Tuesday states. His aides are only now preparing to conduct polls, to the consternation of some Sanders advisers who have hungered for data on his political challenges, like courting black and Hispanic voters.
And rather than benefit from million-dollar contributions through a “super PAC,” Mr. Sanders — who has called such fund-raising groups corrupt — has amassed a million online donations over the past five months, faster than Barack Obama did in his first, digitally groundbreaking, campaign for president.
Mr. Sanders reached a turning point on Wednesday night, when his campaign said that it had raised about $26 million since July — more than Mr. Obama took in for the comparable period in 2007 — and that it had saved enough since the spring to have about $26.5 million in cash.
Mr. Sanders was initially dismissed by political insiders as a fringe candidate running only to push Hillary Rodham Clinton to the left. But he has now demonstrated that he has the resources and the supporters, whom he has only begun to tap financially, to compete for the Democratic presidential nomination.
The great unknown is whether Mr. Sanders can turn his ideologically focused, frugally run movement into a national campaign: Can he expand beyond a fiercely liberal base and attract the broader cross-section of Democrats required to beat Mrs. Clinton, and possibly Vice President Joseph R. Biden Jr.? While Mr. Sanders has 92 paid workers and 24 offices across the early battlegrounds of Iowa and New Hampshire, his operation is still at heart that of a man with a message, lacking the network of political allies across the country and in Congress who can help him build get-out-the-vote organizations that win elections.
“Bernie has done very, very well without having to spend much money at all, relative to Hillary,” said David Axelrod, a Democratic strategist who was a top adviser on Mr. Obama’s campaigns. “His campaign recognizes, rightly, that you have to navigate through the early contests and then, to win on Super Tuesday, you have to spend a boatload. They’ve now proven they’re capable of doing that.”
Mrs. Clinton still holds important advantages over Mr. Sanders: She is better positioned financially thanks to her super PAC — though she only narrowly outraised him since July 1, taking in $28 million; she has far more support among Democratic Party leaders whose superdelegate votes can help secure the nomination; and she has backing among minorities, who can be decisive in some states.
Yet Mrs. Clinton has struggled to put the controversy about her State Department email practices behind her, and her poll numbers have been sliding in Iowa and New Hampshire despite the television advertisements her campaign has run there since August.
Mr. Sanders, who has drawn support by electrifying crowds with his demands for single-payer health care, free tuition at public colleges and higher taxes on the rich, has tested the idea that a modern presidential candidate cannot win without relying on attack ads or internal polling. But he and his advisers, armed with more money than they expected, are now forming a battle plan beyond immediate goals of winning Iowa and New Hampshire.
At Mr. Sanders’s headquarters here on Wednesday, his top advisers met with their lieutenants from Iowa, New Hampshire, and South Carolina — three of the four states with the earliest nominating contests, all in February — to plan the redeployment of dozens of paid staff members thereafter. The workers will go to Super Tuesday states that Mr. Sanders views as winnable — including Colorado, Massachusetts and Minnesota — as well as to Southern states where Mrs. Clinton is expected to perform well, but where close contests could also yield delegates for Mr. Sanders.
Super Tuesday, on which 13 states have scheduled primaries or caucuses, is March 1, 2016.
“With our latest fund-raising numbers, we now know we’ll have the resources to compete everywhere, including all the Super Tuesday states and throughout the South, even Arkansas,” said Jeff Weaver, Mr. Sanders’s campaign manager. “We’ve heard for months, ‘Bernie will flame out after Iowa and New Hampshire.’ But the truth is that we have the resources, and can raise the resources, to go all the way to the convention.”
Mr. Weaver, who spent part of Wednesday interviewing potential staff members in Georgia and Texas, is also working with the campaign’s senior adviser, Tad Devine, on a first round of television commercials to run before Thanksgiving. The Sanders camp is weighing biographical ads to run in Iowa, where Mr. Sanders is less well known than Mrs. Clinton. In New Hampshire, where Mr. Sanders is a familiar presence from his three decades in Vermont politics, a thematic or policy-driven ad may be used first.
The Sanders campaign had considered running ads over the summer. But the candidate’s robust presence on Facebook, Reddit and other influential websites helped draw support and improve his standing against Mrs. Clinton, advisers say.
“We were worried at one point that, without ads, our opponent would be able to define us before we could,” Mr. Weaver said. “But online support for Bernie worked better for us than trying to get people’s attention through TV ads during summer vacation.”
Mr. Sanders now has 650,000 donors, most of whom have not reached the maximum contribution of $2,700.
“I give $20 a month on a recurring payment plan to Bernie, and I hope it helps him take on the billionaires,” said Betsy Butterfield Lynch, a 75-year-old Democrat from Massachusetts who dropped by the Sanders headquarters here on Wednesday to buy Sanders-themed magnets.
For Mr. Sanders to win the nomination, he would need to add large numbers of black and Hispanic voters to his predominantly white coalition of older voters like Ms. Lynch and young people, liberals and working-class families. Yet his campaign has no polling data to know which parts of his message might help him with minority voters. Mr. Devine, who has been pushing the campaign to conduct its own surveys for some time, said the results would not be used to shape Mr. Sanders’s message, but rather to gauge the parts of his message that might have the greatest appeal in particular states or with certain groups of voters that he wants to target.
“I don’t see us having a problem with African-Americans and Latinos — I would call it a challenge — but polling will help us introduce Bernie to more of these voters in the best possible way,” Mr. Devine said. “He is committed to a $15 minimum wage. He has been committed to civil rights and equal justice for his entire career. He fights against income inequality. Polling will help us determine which of these themes will resonate the most in different states.”
Mr. Sanders has used polling in previous campaigns, yet he abhors the message that doing so sends, Mr. Weaver said, that of craven politicians taking their cues from focus groups rather than relying on the authenticity that is Mr. Sanders’s chief selling point.
But Paul Maslin, a pollster who worked for Howard Dean’s 2004 presidential campaign, said that Mr. Sanders would probably need to embrace the virtues of polling.
“Now that they have the money to compete, the Sanders team needs to figure out how to exploit his momentum and win over voters who are up for grabs on Super Tuesday and in other states,” Mr. Maslin said. “And polling will also tell them if the damage done to your opponent is supreme enough that she becomes Humpty Dumpty.”
Inside the campaign offices here, though, Wednesday’s fund-raising results had workers positively giddy at the possibility that, true to Mr. Sanders’s ideals, his campaign could thrive on a powerful message spread through social media and by word of mouth, rather than depending on advertising and polls.
“It’s the same reason we’ll win without a super PAC,” Mr. Weaver said. “Bernie is trying to create a new way of doing politics in America. If enough people support that, we will win.”