DES MOINES — Martin O’Malley is returning to the state that introduced him to presidential politics three decades ago, when he knocked on doors for Gary Hart.
This time he will be promoting himself, in a setting that could determine whether his longshot challenge to Hillary Rodham Clinton for the Democratic nomination takes root or fades away.
The former two-term Maryland governor is expected to enter the Democratic campaign Saturday in Baltimore, where he served as mayor and built his political career. Then it’s on to a union hall in Davenport and more Iowa events before he goes to New Hampshire on Sunday.
Another longshot for the Democratic nomination is expected to announce his candidacy next week: former governor Lincoln Chafee of Rhode Island, who was once a Republican, then an independent, before turning Democrat.
He plans to announce his candidacy Wednesday during a speech at George Mason University in Arlington, Va., spokeswoman Debbie Rich said Friday.
Chafee surprised many when he formed an exploratory committee in April. He has never won elected office as a Democrat and had only discussed his plans with a few family members and supporters.
O’Malley, 52, presents himself as a next-generation leader who built a progressive record in Maryland on gay marriage, immigration, and the minimum wage.
While he has been well received in recent trips to Iowa and New Hampshire, Clinton holds a commanding advantage. And he faces competition for liberal support from Senator Bernie Sanders of Vermont, who has raised more than $4 million since launching his campaign in late April.
Iowa has a history of rewarding insurgent candidates, and O’Malley’s early admirers say he can ill afford any missteps here. President Obama’s defeat of Clinton in the 2008 caucuses serves as the benchmark but few see O’Malley in the same light as the president, who already had an active state organization by this time in 2007.
‘‘I think he needs to win Iowa,’’ said Scott Ourth, a Democratic state representative from Ackworth. ‘‘If he comes into this thing and does not present well in Iowa, it’s pretty much not going to be happening for him.’’ O’Malley spoke at a fund-raiser for Ourth in April.
O’Malley advisers say he will spend significant time in early voting states and be an accessible candidate in diners, coffee shops, and living rooms, no doubt bringing out his guitar at times. That’s what Iowans expect — and may reward — in their leadoff caucuses.
There is ‘‘definitely a path here for him to do well in Iowa if he’s willing to put in resources,’’ said Tom Henderson, chairman of the Polk County Democrats in Des Moines.
O’Malley’s prospective bid holds parallels to the Hart campaign he worked on as a college student in 1983. Hart was a major underdog against former vice president Walter Mondale and struggled in a large field of Democrats.
In late 1983 and into January 1984, O’Malley organized volunteers and canvassed neighborhoods in Davenport and other communities in eastern Iowa, often playing Irish ballads on his guitar at small events, before moving on to help Hart in other states.
Hart’s advisers remember O’Malley as a street-smart, earnest, and detail-oriented young political organizer, constantly building his list of potential caucus-goers for Hart.
‘‘He’s somebody who basically drank up information and knowledge,’’ said Doug Wilson, a Hart campaign aide who dispatched O’Malley to Iowa. ‘‘He was a listener and he was always asking questions. You could tell in his mind that he was pocketing information.’’
Mondale won the Iowa caucuses handily. But Hart emerged as a fresh face in the party, with a surprising second-place finish, went on to defeat Mondale in New Hampshire and dragged out the contest until Mondale was able to grind out enough primary victories to capture the nomination.
This time, Clinton appears to be in a stronger position than Mondale was then. O’Malley supporters hope Iowa can help him become the main alternative to her.
O’Malley has made several appearances in Iowa this year. He has two paid staffers in the state and plans to add more.