Democratic presidential candidates Sen. Bernie Sanders (I-Vt.), left, and former Maryland governor Martin O'Malley. (AP photos)

Bernie Sanders and Martin O’Malley, two candidates vying to become the chief challenger to Hillary Rodham Clinton for the Democratic presidential nomination, crisscrossed Iowa over the past few days, stopping in some of the same cities and marching in small-town Fourth of July parades.

But at this point in the race, they could hardly be in more different places.

During his swing, Sanders, the independent senator from Vermont, drew more than 2,500 people to a convention center here — a record crowd for Iowa. Supporters leapt to their feet and screamed as he decried the “grotesque level” of income inequality in the country and the outsize influence of the “billionaire class” on its politics.

O’Malley’s biggest turnout during his three-day trip was 119 people, who gathered in the side room of a suburban bar outside Des Moines. The former Maryland governor’s pitch included a self-deprecating joke about how little known he remains in the state that will hold the nation’s first caucuses in February.

Presidential politics are replete with candidates who get hot during the summer only to fizzle in the fall. But the early rise of Sanders — a self-described democratic socialist — underscores how hungry the progressive base of the Democratic Party is for a truly authentic alternative to Clinton.

As his crowds have swelled in recent weeks, Sanders’s poll numbers have jumped in Iowa and New Hampshire. O’Malley and the other more mainstream Democratic hopefuls, meanwhile, have stalled in the low single digits. Former senator Jim Webb of Virginia, who jumped into the race Thursday, and former Rhode Island senator and governor Lincoln Chafee have also stepped forward to challenge Clinton.

Scores of interviews suggest Sanders has clearly tapped into the anxieties of recession-weary voters, many of whom feel completely alienated from Washington.

Echoing many others who came to see Sanders here, Steve Pinegar, a 33-year-old heating and air-conditioning technician, said he is looking for someone outside the establishment and said he thinks that Sanders is the only candidate for the Democratic nomination who is speaking to him.

“I don’t want to vote for anyone who’s part of the grand scheme,” Pinegar said, adding that he has grown disillusioned with President Obama’s lack of progress on working-class issues. “I was all hopey-changey last time, but I’m done with that. . . . I feel like me and Bernie Sanders, we could go have lunch and talk about the issues.”

Much of Sanders’s hour-long stump speech focuses on issues that could affect the wallets of workers like Pinegar. Sanders wants to raise the minimum wage to $15 an hour. He wants to guarantee family leave, sick time and vacation time — Americans are working too long, he says. He wants to make college free. And he promises that as president he would make corporations and the wealthy pay more in taxes while trying to cut taxes for those in lower brackets.

“The greed of the billionaire class and corporate America is destroying this great country,” Sanders said Friday night, offering one of a few dozen lines that produced sustained applause from a crowd that included many Nebraskans from across the river.

Building on momentum

Some of Sanders’s largest audiences lately have been in states without early nominating contests, including in Madison, Wis., where he attracted 10,000 people Wednesday.

It was clear from the outset of the race that there would be a bloc of non-Clinton voters, and polling suggests that Sanders — at least for now — has managed to corral most of them. That includes Democrats who were pining to see Sen. Elizabeth Warren (D-Mass.), a darling of the left, get into the race. She has suggested recently that she might campaign for Sanders.

A Quinnipiac University poll released last week showed Clinton drawing 52 percent of likely Democratic caucusgoers in Iowa, with Sanders at 33 percent. O’Malley lagged with 3 percent, followed by Webb and Chafee, with 1 percent each.

Sanders’s numbers have been higher in New Hampshire, where voters are more familiar with him, given his representation of neighboring Vermont. A recent poll from the Granite State showed Sanders trailing Clinton by eight percentage points.

Joe Trippi, a longtime Democratic strategist, said Sanders’s challenge will be to build on the momentum he has established and show that he can demonstrate a broader appeal than just to the party’s left wing.

“If you’re going to run a campaign based on ‘I’m further to the left of the establishment,’ there’s a ready-made audience,” said Trippi, who ran the 2004 presidential campaign of former Vermont governor Howard Dean.

Dean surged in that race based on anti-Iraq war sentiment only to collapse as voting began. Then Sen. John F. Kerry (D-Mass.), a candidate with more establishment support, emerged as the Democratic nominee. Trippi said part of the reason Dean lost support is people began to question whether he was the strongest candidate to beat George W. Bush in the general election.

The O’Malley camp is betting on a similar phenomenon this cycle: that once voters get to know all the candidates better, they will see O’Malley as a more viable alternative than Sanders. O’Malley, 52, has also been casting himself as a part of a “new generation” of leaders, a contrast with both Clinton, who is 67, and Sanders, who is 73.

In an interview following a stop Thursday in Waukee, O’Malley said Sanders has been on the rise partly because voters see him for now as a “protest candidate.”

“People feel like big money has subsumed, taken over, their politics, and they’re frustrated by it,” O’Malley said. “People feel like their voices don’t matter. People feel like they’re not being heard, and right now, they want to protest about that. I’m not running for protest candidate; I’m running for president of the United States.”

O’Malley’s three-day swing has focused on his plan to address climate change by moving the country’s electricity consumption entirely to clean energy by 2050. Aides say other more substantive proposals will help set him apart in coming months.

O’Malley, who served for eight years as Maryland’s governor and seven years as Baltimore mayor, is also increasingly touting his executive experience as an asset. In contrast to Sanders, who talks a lot about legislation he has introduced, O’Malley touts bills that he muscled through in Maryland to legalize same-sex marriage, abolish the death penalty and provide new benefits to immigrants.

“There’s a great distance in saying what we’re for and actually accomplishing things,” O’Malley told a crowd of about 70 people who came to see him at a coffeehouse in Newton on Friday.

Swaying voters

Some analysts suggest O’Malley waited too long to get into the race. By the time of O’Malley’s May 30 announcement, Sanders had already made significant headway with progressive voters looking for an alternative to Clinton.

“People were looking for someone to get in that space, and Martin was playing coy, and Bernie wasn’t,” said one Democratic consultant formerly employed by O’Malley who spoke on the condition of anonymity to speak more freely.

In Newton and elsewhere, there is evidence that O’Malley is making strides with voters that doesn’t show up in a meaningful way yet in the polls.

Susan Daniels, a retired property manager, said she came to the event in Newton “to expand my horizons” by hearing from a candidate she didn’t know much about. She left inclined to caucus for O’Malley, impressed by his command of details without notes. She also has nagging doubts about supporting Clinton.

Interviews, however, also suggest that Sanders supporters might be harder to peel off than people think. While some who attend his events are still shopping for a candidate, many arrive already sold.

Daryl Kothenbeutel, a retired owner of a prairie seed business, drove about 90 minutes from Clear Lake to Fort Dodge on Thursday to see Sanders for the third time in recent weeks. He said he has been most impressed with Sanders’s commitment to fighting climate change and that he likes his other prescriptions for the country.

“The man, I think, is our last hope for America. I really do,” said Kothenbeutel, 71. “Hillary seems to bring up everything after Bernie does,” Kothenbeutel said.

Tad Devine, a strategist for Sanders, said he thinks Sanders’s support will continue to grow, in part because he has the ability to attract new voters to the race, as Obama did in 2008. Once party elites begin to understand that, Devine suggested, he said he thinks Sanders has the potential to win more backing from the Democratic establishment.

Sanders made headway with endorsements over the weekend in New Hampshire, winning the support of longtime party activist Dudley Dudley.

Dudley, who in the 1970s became the highest serving woman in the state’s history as an executive councilor, hosted a house party in Durham for O’Malley just two months ago.

She told CNN that she has nothing against O’Malley, but she likes the way Sanders delivers his message.

“He has a way of stating it in a way that is no-nonsense and so straightforward,” Dudley said.