Burlington, Vermont (CNN) It wouldn't be the first time a revolution sparked in New England changed the world.

But two and a half centuries after the insurrection that birthed America, the idea that a rumpled radical like 73-year-old Vermont socialist Bernie Sanders could overthrow the U.S. economic, health care and tax systems seems farfetched at best.

Yet that's exactly the task the fiery U.S. senator has set himself in a presidential campaign targeting billionaire "oligarchs" who he says have hijacked America's economy and inflicted misery on the middle class.

Sanders, an agitator who doesn't suffer fools, political opponents or journalists gladly, is testing whether the kind of populist, liberal agenda that gave him 75% approval ratings in his adopted home state can catch fire nationwide.

"Brothers and sisters: Now is not the time for thinking small," Sanders told thousands of supporters in Burlington on Tuesday.

"Now is not the time for the same-old, same-old establishment politics and stale inside-the-Beltway ideas," Sanders said in an implicit denunciation of the runaway front-runner for the Democratic nomination, Hillary Clinton.

The obstacles Sanders faces in the presidential primary race, however, are immense.

Sanders has no viable countrywide political organization, so he must foment a grassroots uprising. His task is complicated by the fact that although he caucuses with the Democrats in the Senate, he has always been a political independent wary of formal party affiliations.

Taking on the Clinton machine

He must take on the Clinton political machine that has retooled after its defeat in 2008. He's a minnow in the money game in a campaign that will be awash in billions of dollars.

He's not exactly a polished pol either, with an unrepentant message of class warfare that makes him an unlikely candidate to win over Middle America.

And many Democrats are only beginning to learn who Sanders actually is. He's a long shot, but has shown some momentum since indicating he would take the plunge into the presidential race late last month. In a new Quinnipiac University poll released on Thursday, Sanders was at 15% of Democratic voters nationwide, up from the 5% he managed in a CNN national poll last month.

His campaign launch, on a Lake Champlain boardwalk that he saved from developers as Burlington's mayor, had the air of a hippie revival or a folk festival.

One woman twirled a hula hoop and shouted "Hooping for Bernie"; people lined up for free helpings of locally made Ben and Jerry's ice cream; and kids carried banners naming Sanders their political superhero. Vermont-based warm-up act Mango Jam pumped out a fusion of Zydeco, Cajun and Caribbean rhythms.

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The place pulsed with the hopeful political energy that is unique to the start of U.S. presidential campaigns when anything seems possible -- even in minute, ultraliberal blue states with three electoral votes.

Of course, in the highly unlikely scenario that Sanders is elected president, enacting his revolutionary agenda faces even greater odds. Another long-shot, transformational president has already demonstrated how hard turning campaign slogans into reality can be.

If there's one lesson of Barack Obama's White House, it's that passing social reforms such as Obamacare -- which falls way short of the kind of single-payer health system Sanders prefers -- can be almost impossible and exact a heavy political price.

Sanders surely knows this.

He might be a dreamer, but he knows the realities of politics: A pragmatic streak leavened his idealism during four terms as mayor; he railed against the Iraq war but became a champion of veterans in the Senate.

So it may be fair to question whether, unlike his devoted Vermont cadres, a politician as experienced as Sanders thinks he can actually win the presidency, especially as political reality is weighted against him.

America's middle class, while hurting, is hardly a simmering proletariat ready for the economic shock therapy he prescribes.

Opponents attack Vermont's record

And political opponents argue that for all his flamboyance, Vermont has not done that well in the Sanders era.

"Fear and frustration are a powerful political cocktail," said a statement from the Vermont Republican Party on Tuesday.

"All you have to do is take a good look at Vermont's demographic and economic realities -- and our growing crisis of affordability -- to get a good look at what the hangover from a Sanders administration would look and feel like."

But to simply write off the Sanders campaign as some kind of personal vanity project, or a token quest to insert progressive values into the 2016 campaign, does him an injustice.

His messages, the timing of his campaign, the polls and his personal qualities suggest that the Sanders campaign could end up more than a flight of political fancy and become a real headache for the Clinton machine.

For starters, the 2016 Democratic primary campaign seems to be shaping itself around the issues of economic justice and fairness for which he first fought amid the political turmoil of 1960s Chicago where he was a student.

In a recent interview with CNN, the candidate's UK-based brother Larry disputed the notion that Sanders is a man of the fringe.

"I don't think we are out of the mainstream. I think that what we have noticed is that the mainstream has been ignored for a long time," he said.

While the solutions that Bernie Sanders advocates to fix America's problems are radical, his diagnosis of the national mood is not.

Health care, child care, college and medical costs preoccupy middle class families, whomever they vote for, a fact reflected in the way Clinton and Republicans Marco Rubio, Jeb Bush and Rick Santorum have emphasized income inequality in their campaigns.

One advantage Sanders may have over this crowd is the crucial elixir of presidential runs -- "authenticity" -- said Vermont University political science professor Garrison Nelson, who has known Sanders for decades.

"Bernie Sanders has been saying these same things for over 40 years. Bernie is not tailoring his speeches to the agenda. The agenda has caught up with Bernie Sanders."

Another way Sanders debunks the hopeless crusade metaphor is that he's not just some political gadfly. He narrowly won his first race for mayor, then got elected over and over again, and has been in Congress for a quarter century.

Iowa could be a tough sell for Sanders

But it's not a given that his brusque style and pyrotechnical calls for a revolution will go down well in Iowa, for instance, where voters like to be wooed rather than harangued.

"It is going to be a hard sell," said Nelson, who said his friend must find a sweet spot on the issue of income inequality. "Bernie is counting on that -- that degree of resentment and that degree of anger."

While Sanders is a novelty in Iowa, he's a known commodity in New Hampshire -- where the overlap from the Burlington media market makes him well-known and could give him a leg up in the primary campaign.

But Sanders must also show that he has got the financial muscle to even get that far -- though he says he is certain he can raise $50 million, after quickly pulling in contributions of around $4 million within days of first saying he would run for president.

"That should give him enough money to be competitive in the four early states," said Eric Davis, a veteran Vermont political analyst and professor emeritus at Middlebury College, referring to Iowa, New Hampshire, South Carolina and Nevada.

But Davis asked: "What state is his campaign going to be in at the end of those four early contests?"

And if by some miracle he won the nomination, he would then find it difficult to counter questions about whether his left-wing politics would be palatable to a wider electorate.

Still, polls suggest that Sanders is a viable candidate to be the leading alternative to Clinton among Democrats -- though he lags behind the former first lady by 50%.

A Quinnipiac University poll in Iowa found that 15% of likely caucus goers would back him while 18% of likely Democratic voters in New Hampshire prefer him -- numbers that give him a genuine platform in the race.

He's ahead of other possible Democratic long shots, including former Maryland Gov. Martin O'Malley and former Sen. Jim Webb of Virginia.

And while he may not beat Clinton, Sanders can at least shape the economic debate in the Democratic primary and force her to confront her liabilities on trade and the influence of big money in politics.

Appealing to liberal Democrats

Clinton will also be wary of alienating liberal Democrats who support Sanders and are suspicious of her candidacy, but whom she needs to swell her margins in Midwestern swing states if she is to win the general election.

Sanders' hopes of causing a stir in 2016 also depend on his capacity to show the side of his character that has won him such a loyal following in Vermont, where he has convinced voters he is on their side.

Ann Taylor of Burlington, a self described "old hippie," said Sanders was pushing a message that America needed to hear: "This is probably the only candidate that is going to fight for working people. And I know he is influencing Sen. Clinton. Bernie will do so much for working people, it is unbelievable."

It's rare to find a lawmaker or leader who is as beloved on his home turf as Sanders. The key to his popularity may lie to some extent in Vermont's compact geography and a population that is much smaller than that of many American cities. He will have a harder time making personal connections in a presidential race.

So the fate of the Sanders campaign likely lies in whether the rest of America, and not just liberal Vermont, is hankering for a liberal class warrior who shoots from the lip.