BOULDER — Hillary Clinton’s worst nightmare could be voters like Kelly Sprague of Denver.

Despite intense sun and no shade, Sprague waited more than two hours Saturday for a campaign appearance by Vermont Sen. Bernie Sanders at the University of Colorado Boulder’s Potts Field, which drew a crowd estimated at 9,000.

Needless to say, she’s a Sanders fan. And while she can’t imagine herself voting for a Republican, neither is she thrilled with the prospect of throwing her support to Clinton if she defeats Sanders for the Democratic presidential nomination.

“I don’t know what I’ll do if that happens,” Sprague said. “I think I would have to read a little bit more and watch a little bit more than I have so far on her perspective. I feel like she’s kind of the same old thing that we’ve been hearing, just with a different look.”

Much has been made of the intraparty warfare in the GOP presidential primary, but Democrats are wrestling with their own division, as large swaths of younger and more progressive voters reject Clinton and flock to the avowedly anti-establishment Sanders.

Clinton, a former secretary of state and U.S. senator, remains the favorite to capture the Democratic nomination in what has emerged as a two-candidate race, although Vice President Joe Biden could upend that dynamic if he enters the fray.

The danger for Democrats is that the frontrunner Clinton could win the primary but lose the enthusiasm of the party’s left wing, where she’s viewed as politics as usual, as the November 2016 election approaches.

Clinton has moved to reach out to voters on the left by, for example, coming out against the Keystone XL pipeline and the Trans-Pacific Partnership trade agreement negotiated by the Obama administration.

But that approach has backfired with some Sanders backers.

“He can’t be bought. She’s a bandwagoner,” said Carolina Bueno, a University of Denver graduate student. “She jumps on the hot topic of the day.”

She and her friend Moses Izeta of Thornton said they would consider writing in Sanders on the general election ballot if he loses the primary to Clinton.

“It’s a tough question because if it came down to it, I don’t want the Republican Party to win. So it would be a really hard decision,” said Izeta, a charter-school dean. “I probably would write him in, depending on how close he lost the nomination by.”

Having said that, Izeta added that he’s confident Sanders can continue to build on his momentum and capture the Democratic nod. Polls show Sanders chipping away at Clinton’s lead, particularly in early caucus and primary states Iowa and New Hampshire.

“If we all vote, and the way the crowds are showing up to his events, I don’t see why not, it should be a landslide,” Izeta said.

At the rally, Sanders stuck to his talking points, vowing to fight against income inequality, push for immigration reform, work to raise the minimum wage and take on Wall Street and the Supreme Court’s Citizens United campaign-finance ruling.

“Brothers and sisters, our job is to create an economy that works for all of us and not just the billionaire class,” Sanders told the cheering crowd. “We are sending a message to the wealthiest, most powerful people in this country, and that message is, ‘You cannot have it all.’”

One of those introducing Sanders was anti-fracking activist Micah Parkin of 350 Colorado, who last week spoke at a statehouse rally that singled out Democratic Gov. John Hickenlooper for criticism over his pro-fracking positions.

“He [Sanders] has worked consistently to address the climate crisis,” Parkin said. “He has said climate change is the greatest threat facing the planet, and he’s right.”

The 74-year-old Sanders, elected to the Senate as an independent, drew loud cheers for embracing the anti-establishment mantle.

“This is a people’s campaign, and you brothers and sisters are part of a political revolution,” Sanders said. “This is a campaign that is taking on the establishment at every level of society.”

His supporters praised his willingness to adopt stances other candidates reject.

“I really support his integrity. I love the fact that he’s saying all the things that progressives and liberals have been afraid to say, or any of our politicians,” Bowman said. “None of our representatives with the exception of (Massachusetts Sen.) Elizabeth Warren have had the integrity or willpower to say, ‘This is wrong, we need to change these things about the way we’re running our country.’”

Even so, Bowman said she wouldn’t hesitate to back Clinton if she wins the nomination, especially if businessman Donald Trump becomes the Republican nominee, a possibility she described as “frightening.”

“It’s a disappointment [if Clinton wins], because it would be really nice to be unequivocally supportive of a candidate,” Bowman added.

Her friend Ray Tuomey, a Boulder entrepreneur, said if Sanders lost and it came down to Clinton and Biden, he would vote for Biden. Biden hasn’t said whether he will enter the race, although advisers reportedly say he’ll make a decision by the end of the week.

“I would just say that Hillary seems to be more of the traditional political bent,” Tuomey said. “Also, I don’t really like the idea of a Bush dynasty, I don’t really like the idea of a Clinton dynasty as much.”

Still, Clinton’s bid to become the first female president resonates with Sanders supporters like Bowman and Tuomey, who agreed they would like to see a woman in the White House.

University of Wyoming student Martha Tate, who drove from Laramie to the Boulder rally, called Sanders “a breath of fresh air.”

“He’s really speaking on platforms that other people feel they can’t win on,” Tate said. “I have a lot of hope that the more people will show up, the more people are going to see it [a Sanders win] is realistic.”

As for Clinton, “She has a pretty polarizing effect,” said Tate. “I think she’d be just the same as any other politician, whereas I feel he’d be interesting and real, and maybe make Republicans and people from different sides look into him, because they already know her.”

The enthusiastic turnout demonstrates that Sanders hasn’t lost his appeal in Colorado, where he drew 5,500 at a campaign appearance in June at the University of Denver.

What’s different is that a growing number of Sanders supporters no longer see him as a protest vote but as a viable candidate who can beat Clinton and win the nomination.

“If the numbers continue at this pace between now and 2016, we should be fine,” Izeta said.

— valrichardson17@gmail.com

Photo of Bernie Sanders addressing supporters on Oct. 10 in Boulder by Pat Duncan/The Colorado Statesman.