DES MOINES -- Two of Hillary Rodham Clinton’s rivals for the Democratic presidential nomination staked out liberal positions on issues including income inequality, trade and Wall Street reform ahead of her planned appearance in Iowa on Saturday.

Sen. Bernie Sanders (I-Vt.), who’s been rising in the polls but remains well behind Clinton, drew close to 800 people Friday night at Drake University and then opened an office here Saturday morning, while former Maryland governor Martin O’Malley attracted smaller but enthusiastic crowds in a series of appearances Thursday.

In the midst of a three-day swing through the first caucus state, Sanders told supporters crammed into his new office here that the grass-roots nature of Iowa politics is ideal for the “revolution” he is waging and that he is confident “we’re going to win this thing.”

“What I like about the process here in Iowa is it’s very grass-roots, and you’re looking at a grass-roots guy,” Sanders said, speaking to about 40 people crammed into a small suite in the same office complex where Clinton has space in Des Moines.

Sanders also ticked off several issues on which he differs with Clinton or on which he said Clinton hasn’t taken a clear position. They included his opposition to authorizing the Iraq war; his support for a $15 minimum wage; his opposition to the proposed Keystone pipeline; and his opposition to the “disastrous” Trans-Pacific Partnership, a proposed trade deal supported by President Obama.

“I don’t understand how you don’t have a position on this issue,” a feisty Sanders said of Clinton.

The night before, Sanders received a rock-star like reception as he stepped on stage in a packed university auditorium.

“Whoa, got a lot of people here tonight,” Sanders said. “You know, sometimes our campaign has been referred to as a fringe campaign. Well, if this is fringe, I would hate to see mainstream.”

Over the course of the next 90 minutes, Sanders, a self-described democratic socialist, decried the influence of the “billionaire class” over American politics and the “grotesque level of wealth and income inequality” in the country.

“That is something that we are going to change,” he told a crowd that repeatedly interrupted him with applause and screaming cheers.

Sanders, who has been criticized recently for not talking enough about immigration issues, also added a section to his stump speech Friday calling for "a rational immigration process," voicing opposition to "the Republican alternatives of self deportation or some other draconian non-solution." Sanders said he backed Obama's stance “to do through executive action what the Congress refuses to do through legislation.”

O’Malley touched on many of the same issues Thursday during a swing that included house parties in Marshalltown and Mount Vernon and an appearance at a pub in Iowa City.

O’Malley was also peppered with questions from reporters and some in his audiences about how he plans to compete against Clinton, a formidable front-runner, and Sanders, who is drawing larger crowds on the trail.

“I can tell you that I represent new leadership,” O’Malley told a crowd of more than 100 people packed into a side room at the Iowa City pub. “I am the only candidate in this race with 15 years of elected executive experience at getting things done. I have progressive goals and progressive values. I never apologize for them, and I have a track record of forging public opinion, not following it, and that’s called leadership, and that’s why I think I’d be better.”

O’Malley, who served as mayor of Baltimore for seven years and as Maryland governor for eight years, called for “a sensible rebalancing” of an economy that he said has become too heavily stacked in favor of the wealthy.

During an appearance in the Marshalltown living room of Mark Smith, the minority leader of the Iowa House of Representatives, O’Malley asked for a show of hands from those who feel they have a better lot in life than their parents and grandparents. Nearly every hand in the crowd of about 60 people went up. But hardly anyone raised their hand when he asked if they felt confident they could provide a better life for their children and grandchildren.

“I’m running for president because of that hard truth we now share,” O’Malley said, later offering a similar message to a crowd of about 80 people at a house party in Mount Vernon.

O’Malley also talked a good deal about his record as governor, which included legalizing same-sex marriage, expanding immigrant rights, abolishing the death penalty and raising the state’s minimum wage.

“Most of my experience has been in getting things done,” O’Malley said.

O’Malley has a series of appearances scheduled Saturday in New Hampshire, the nation’s first primary state.

Sanders is planning to open his Iowa headquarters in Des Moines on Saturday morning before heading to events in Marshalltown and Cedar Rapids. He has appearances planned Sunday in Waterloo, Iowa Falls and Indianola.

Another potential Democratic rival to Clinton -- James Webb, the former senator of Virginia -- plans to spend several days in Iowa starting Sunday.