Former Maryland governor Martin O'Malley officially kicked off his 2016 presidential campaign in Baltimore on Saturday morning, offering himself to Democrats as a younger and more progressive alternative to front-runner Hillary Clinton. (AP)

Former Maryland governor Martin O’Malley launched his long-shot White House bid Saturday with populist attacks on corporate giants, big banks and political dynasties, offering himself as a younger, more progressive alternative to Hillary Rodham Clinton.

“We cannot rebuild the American dream here at home by catering to the voices of the privileged and the powerful,” O’Malley told a sweaty crowd at Baltimore’s Federal Hill Park before coming here to campaign in the nation’s first presidential nominating state. “Let’s be honest. They were the ones who turned our economy upside-down in the first place. And they are the only ones who are benefiting from it.”

Even as a few protesters at the park sought to link O’Malley’s time as Baltimore mayor to recent unrest in the city, he said the rioting there underscored an urgent need to invest in struggling communities.

“The scourge of hopelessness that happened to ignite here that evening transcends race or geography,” he said. “The hard truth of our shared reality is this: Unemployment in many American cities and in many small towns across the United States is higher now than it was eight years ago. Conditions of extreme and growing poverty create conditions for extreme violence. We have work to do.”

O’Malley will visit New Hampshire, another early nominating state, on Sunday. Creating a base of support there and in Iowa is crucial to his upstart strategy. He is banking on the prospect that Clinton’s dominant popularity will crater as more voters assess the baggage she brings to the race, and that he will emerge as the most credible alternative.

Despite multiple trips to key states over the past two years, O’Malley remains largely unknown to voters and registers in the low single digits in polls. Sen. Bernie Sanders (I-Vt.), the only other declared Democratic candidate, has had early success courting liberals, drawing boisterous crowds in Iowa in the past week. But few give Sanders, a self-described socialist, any chance of winning the nomination.

Other potential hopefuls — including former senator Jim Webb (Va.) and former senator and governor Lincoln Chafee (R.I.) — have not invested the time that O’Malley has in laying the groundwork for a serious run.

H. Boyd Brown, a South Carolina Democrat, said that he and other O’Malley backers are hoping for a repeat of the 2008 primary contest, in which front-runner Clinton succumbed to Barack Obama, then a largely unknown junior senator from Illinois.

“Her support then, as it is now, was a mile wide and an inch deep,” Brown said in an interview. If O’Malley can manage a strong showing in Iowa — where he plans to camp out in the coming months — “the dynamics completely change, and it’s game on.”

O’Malley’s faith in his prospects is fueled in part by an early political experience, working on the 1984 campaign of underdog Gary Hart, who exceeded expectations in Iowa, won in New Hampshire and became the chief rival to former vice president Walter Mondale, the eventual nominee.

Former Maryland Gov. Martin O'Malley on gay marriage, income inequality and more, in his own words. (Julie Percha/The Washington Post)

The lesson? “That the impossible really isn’t,” said Trevor Cornwell, a Palo Alto technology executive and one of several former Hart aides who traveled to Baltimore for O’Malley’s announcement.

Other Democrats, including Senate Minority Leader Harry M. Reid (Nev.), have called the comparisons to Obama a pipe dream, noting that Clinton’s polling numbers are stronger than any non-
incumbent president in memory.

American University presidential historian Allan Lichtman said that he sees nothing in O’Malley’s pitch that is likely to change the dynamic of the race.

“He has a mountain in front of him, and that mountain would have to implode,” Lichtman said.

O’Malley, who endorsed Clinton in 2008, called the former secretary of state on Friday to inform her of his launch. The two exchanged tweets Saturday, with Clinton welcoming O’Malley to the race and O’Malley replying that he was “eager to engage in a healthy debate about our visions for America.”

At a union hall here Saturday afternoon, O’Malley seemed almost giddy to be an official candidate after years of travel to help other Democrats and months of buildup. He was greeted by a standing ovation from a crowd of nearly 100, a mix of supporters and people who said they wanted to size him up.

“I believe people in Iowa are looking for alternatives,” O’Malley told reporters who peppered him with questions about taking on Clinton. “We’re going to go out and campaign hard and offer ideas that will move our country forward, and that’s how we’re going to succeed.”

In Baltimore, O’Malley called for boosting the minimum wage, comprehensive immigration reform, combating climate change and breaking up big banks, noting that the chief executive of Goldman Sachs recently “let his employees know that he’d be fine with either Bush or Clinton” in the White House.

“I bet he would,” O’Malley said, drawing some laughter. “Well, I’ve got news for the bullies of Wall Street. The presidency is not a crown to be passed back and forth between two royal families.”

Many of Maryland’s top Democrats are backing Clinton, and only a few came to O’Malley’s campaign launch. But the event inspired Bart McNeill, who drove from Lancaster County, Pa., in hopes of hearing the progressive themes O’Malley articulated.

“I know he’s an underdog still,” McNeill said. “But I’d like to see some sort of fight against Hillary. I don’t think she should just be anointed the Democratic candidate.”

O’Malley recounted several of his legislative victories Saturday, including the legalization of same-sex marriage, abolition of the death penalty, tougher gun control and a boost in Maryland’s minimum wage.

In recent weeks, O’Malley has moved to draw distinctions with Clinton on issues such as trade and immigration and has accused her of embracing liberal positions on issues such as same-sex marriage because they poll well among Democratic activists.

“We will not stick our finger in the air to see which way the wind is blowing,” a narrator says in a video O’Malley sent to supporters Saturday.

Maryland spent record amounts on education while O’Malley was governor, despite the recession, and saw steep drops in crime and a dramatic increase in people covered by subsidized health care.

Those achievements were made possible, in part, by a string of unpopular tax increases that helped propel Gov. Larry Hogan (R) to victory in last year’s election. Hogan’s win was cited by the Republican National Committee in an briefing book on O’Malley released Friday, which chortled that the Democrat was too liberal even for deep-blue Maryland.

The former governor, who is 15 years younger than Clinton, argues that he is best suited to represent a new generation of Americans, a contrast drawn bluntly last week by the leader of a new O’Malley super PAC called Generation Forward.

“This is not your grandmother’s super PAC,” Damian O’Doherty said, more than once. A spokesman said he was referring to the modern tactics the PAC plans to employ and not to Clinton, whose first grandchild was born last year.

But the contrast with O’Malley — who still plays in a Celtic rock band at age 52 — seemed obvious.

But some Clinton boosters question O’Malley’s claim to be the candidate of tomorrow.

“I have to admit to smiling when I heard him describe his candidacy as about the future, not the past,” said Lanny Davis, a former lawyer for President Bill Clinton and longtime friend of Hillary Clinton who supported O’Malley in his gubernatorial runs. “He is running against someone who would be the first woman president of the United States.”

O’Malley’s personal finances also set him apart from the Clintons, who each have made millions from paid speeches.

As mayor and governor, O’Malley — who does not come from a wealthy family — had limited outside income. His wife, Catherine Curran O’Malley, is a district court judge. After leaving the governor’s mansion, the family moved into a $549,000 home in Baltimore, taking out a mortgage to purchase it.

Some Democrats say they suspect that O’Malley’s White House bid is aimed at becoming Clinton’s running mate, or perhaps winning a Cabinet post in her administration. He has insisted that is not the case.

“I’ve never run a bad race,” he told the crowd here in Iowa. “I’ve often started as an underdog.”

Arelis R. Hernández in Baltimore contributed to this report.