DES MOINES, Iowa — Martin O’Malley’s latest foray into Iowa begins, appropriately, in a place called Clinton.

The Maryland governor, a Democrat, is filling the void in Iowa, New Hampshire and beyond during the early stages of the 2016 presidential race, campaigning for fellow Democrats and making personal appeals while former Secretary of State Hillary Rodham Clinton remains the prohibitive — if yet undeclared — favorite.

In the summer before November’s mid-term elections, Clinton’s dominant position in a hypothetical field has limited Democrats’ activities in early presidential voting states even while an ambitious slate of Republicans descend. Active Democrats here say O’Malley has become an exception, cultivating relationships and developing a reputation as a loyal foot soldier for the party.

“He’s doing more than anybody else,” said Mike Gronstal, the Iowa Senate Democratic leader. “Others have indicated they are interested in doing some things. But we haven’t seen it yet.” He declined to name the other Democrats who have inquired.

O’Malley is laying the groundwork for a presidential campaign whether or not Clinton runs, although it remains unclear if he will challenge the popular former first lady. O’Malley was the second governor to endorse Mrs. Clinton’s presidential campaign in 2007 and maintains ties to former President Bill Clinton, who brought the then-Baltimore mayor to Northern Ireland on a presidential delegation trip in 2000 and appeared in an ad for O’Malley during his first campaign for governor.

As his second term in Maryland ends, O’Malley has visited New Hampshire twice since November and raised money for Gov. Maggie Hassan, Sen. Jeanne Shaheen — a fellow alumnus of Gary Hart’s presidential campaigns — and Rep. Annie Kuster. In South Carolina, O’Malley has held events for Vincent Sheheen, who is challenging GOP Gov. Nikki Haley, and Bakari Sellers, who is running for lieutenant governor.