MANASSAS, Va. - Waving her rainbow-colored "Get Bernie on the Ballot" sign at a county fairground two hours south of the Mason-Dixon Line, Liz McCauley had no qualms in standing up in her pink tennis shoes for a presidential hopeful who calls himself "a democratic socialist."

After all, the 40-year-old lifelong Republican and former "Marine brat" says, she's stood down her dad and her brother - both Corps veterans - when they "sputter 'Socialist!' " at the mere mention of Vermont Sen. Bernie Sanders.

"The theocratic extremists have sort of pushed the moderates to the side," she said of her decision to ditch the GOP. But what really drew her to Sanders was pure bread-and-butter: the candidate's call for free public college tuition and for expanded family leave that would help her care for her ailing husband.

"To let my daughter know that she might be able to afford the education that she's earned, without indebting myself for the rest of my life!" McCauley said hopefully, as a crowd that swelled to about 2,000 for a nighttime rally kept streaming over the rolling hillside.

As the 2016 presidential race shifts into second gear, converts like McCauley are what's behind something that pundits once called unthinkable: the rise of a wonky, rumpled and mildly dyspeptic 74-year-old senator into the early lead in the key Democratic battlegrounds of Iowa and New Hampshire.

And as Sanders steadily gains on long-anointed front-runner Hillary Clinton in national polling, a few even wonder out loud if the question for 2016 is no longer just, "Isn't it time for a woman in the White House?" . . . but now, also, "Is America ready for a socialist?"

Monday night in Manassas - the climax to a sometimes audacious Sanders weekend swing through the heart of the politically red South - showed both the promise and pitfalls as Sanders seeks to take his campaign, fueled by a tankful of indignation over income inequality, to a national audience.

Some candidates adapt the message to the locale. Not this candidate. Exurban Virginia's Prince William County - where Confederate Civil War victories still echo, even after it was captured by President Obama in the 2012 election, with help from a surging Latino vote - got the same message that big crowds in hipster havens like Portland, Ore., heard this summer.

"We are the 99 Percent, and we will take back power from the 1 Percent!" thundered Sanders, his voice raw and hoarse after a long day on the trail, as darkness enveloped the outdoor rally. The cry was a seemingly conscious echo of the Occupy Wall Street movement that flared four years ago this week, with complaints against America's wealth gap that now form Sanders' platform.

"It's not a radical, left-wing idea to say if a person works 40 hours a week, that person should not live in poverty," Sanders added, to a boisterous cheer. He called for a $15 minimum wage and pushed his plan for free tuition at public colleges and universities, to be paid for in part by a tax on Wall Street speculation.

A 'Greek chorus'

The senator's most enthusiastic supporters - packed in the bleachers behind him - at one point began a chant of "Get Wall Street! Get Wall Street!"

"It's like having a Greek chorus," said a bemused Sanders, chuckling at one of the few light moments of a nearly one-hour speech with the vibe of a passionate, serious college lecture - stripped of the political theater that dominates most American politics in the high-def era.

From his supporters, three reasons for early enthusiasm for Sanders came up again and again: his concrete proposals that would help the middle class with tuition or medical bills; disgust with big-money politics and praise for the senator's reliance on small donors; and the consistency of the story arc that started with campus activism in the 1960s.

The crowd was an unusual blend - including a decent helping of baby boomers with a touch of gray and liberal political views forged in the wake of the 1963 civil-rights March on Washington, which Sanders attended.

But perhaps the largest bloc was composed of twentysomethings and teens, born long after Sanders' unlikely rise to become mayor of Burlington, Vt., in the 1980s. The first-time voters harped on what they saw as the pure authenticity of a candidate old enough to be their grandfather.

"I love his sincerity," said Hannah Andes, 18, her sunglasses framed by flowing hair dyed a bright pink, a Starbucks Frappuccino in one hand and a "Sanders 2016" bumper sticker in the other.

Andes, who lives here and attends a nearby community college, said she began to support Sanders a couple of months ago after googling the views of the leading candidates. She liked where Sanders stood on gay rights, and now she's lobbying her college friends to join the cause.

But the rally here also highlighted what at this point - still 4 1/2 months before the first caucus in Iowa - seems Sanders' biggest hurdle: a struggle to make major inroads with black and Latino voters, who have outsize influence in Democratic primaries.

Despite a large Hispanic community in Manassas, few if any were in evidence at Monday's rally, with a smattering of African-Americans in the crowd.

Larry Sabato, a University of Virginia historian and political analyst, said by phone that Clinton's name and familiarity, and a sense that she deserves a shot at the Oval Office, have made it difficult for rivals to gain traction with minorities.

"Bill Clinton was 'the first black president,' and now we're back to this," Sabato said of Hillary Clinton's steady black support. He added that a possible candidacy by Vice President Joe Biden would further complicate things.

But one black voter at the rally - Preston Miller, 31, from the Maryland suburbs, who works in cybersecurity for what he would only call "an agency with three letters" - seemed won over.

Miller also used works like "authentic" and "refreshing" to describe Sanders, praised his refusal to attack the other candidates, and said that even if Sanders is a long-shot to become the 45th president, he's already made liberal ideas a bigger part of the 2016 election.

"He's influencing the conversation," Miller said.