Martin O'Malley, former governor of Maryland and potential Democratic presidential candidate, listens to attendees during a Scott County Democratic Party dinner in Davenport, Iowa. (Daniel Acker/Bloomberg)

Former Maryland governor Martin O’Malley took a swipe at likely 2016 contenders Hillary Rodham Clinton and Jeb Bush on Sunday, saying that “the presidency of the United States is not some crown to be passed between two families.”

Appearing on ABC’s “This Week,” O’Malley, who is weighing a possible run against Clinton for the Democratic nomination, called the presidency “an awesome and sacred trust to be earned and exercised on behalf of the American people.”

O’Malley — who at times has been reluctant to take on Clinton directly — declined to say whether he thought the former secretary of state would stand up to Wall Street and other special interests. “I don’t know where she stands,” he told host George Stephanopoulos. “Will she represent a break with the failed policies of the past? Well, I don’t know.”

O’Malley is trying to position himself as a more liberal and forward-looking alternative to Clinton, who holds a commanding lead in early polls among Democratic voters and is expected to make her bid official next month.

Some Democrats have speculated that O’Malley is angling to be Clinton’s vice presidential candidate or a Cabinet secretary. He has been loathe to criticize her on some counts, including her practice of using a private e-mail account for government business.

But in recent trips to early nominating states, O’Malley has tried to draw distinctions with Clinton on issues such as banking regulation and immigration. O’Malley, who returns to New Hampshire this week, has sounded a lot like Sen. Elizabeth Warren (D-Mass.), a crusader for the middle class whom many in the party’s liberal wing are urging to run for president.

O’Malley was one of the first governors to endorse Clinton when she sought the Democratic nomination in 2008. Reminded of that by Stephanopoulos on Sunday, O’Malley said Clinton was the most prepared candidate “for those times. . . . I think our country always benefits from new leadership and new perspective.”

The Democrat pitched himself as an executive with 15 years of experience — eight as governor of Maryland and seven as mayor of Baltimore — who has accomplished a good deal and knows how to get things done. Among the achievements in Maryland he mentioned were several “policies of inclusion,” including the legalization of same-sex marriage and measures to benefit immigrants.

He reiterated that he plans to make up his mind about a White House bid this spring. Aides said that his tone Sunday wasn’t part of a calculated shift in strategy and that he is continuing to weigh methodically whether to move forward.

Stephanopoulos said he was surprised by the forcefulness of O’Malley’s answers. “I wasn’t expecting you to be this direct,” the host said. But when Stephanop­oulos asked which two families he was referring to when discussing the presidency, O’Malley demurred, saying it could be “any two families.”

Several of O’Malley’s boosters said they appreciated what sounded like a more aggressive approach.

“I liked the assertiveness there,” said H. Boyd Brown, a member of the Democratic National Committee from South Carolina, who is supporting O’Malley in that early primary state. “It had me a little pumped up this morning.”

Brown said he often hears concerns from local Democrats about another Clinton or Bush in the White House. “That’s a complaint I hear, that America has more than two families,” Brown said.

Dan Calegari, a Democratic activist helping make introductions for O’Malley in New Hampshire, echoed that sentiment, saying, “People are dying for somebody to tell the truth.”

O’Malley spoke more cautiously when Sunday’s interview turned to foreign policy. Pressed by Stephanopoulos, O’Malley said that a nuclear-armed Iran — and related “extremist violence” — would present the greatest “man-made” danger to U.S. interests.

He was highly critical of the 47 Republican senators who recently signed an open letter to Iran’s leaders over negotiations on that country’s nuclear program.

“If you hate the president of the United States more than you distrust the ayatollah, then you probably shouldn’t be in the United States Senate,” O’Malley said.

He also said that Maryland has “passed some of the earliest and strongest sanctions against Iranian nuclear development of any state in the nation.” Aides cited 2012 legislation that barred companies from doing business with Maryland if they were invested in Iran, and a 2008 measure that divested the state’s retirement and pension system from companies that do business in Iran’s energy sector.

O’Malley brushed off questions about lack of enthusiasm for a White House bid expressed by fellow Marylanders in an October poll published by The Washington Post.

That poll showed that Clinton was the choice for president among 63 percent of Maryland Democrats, while O’Malley drew the support of 3 percent.

“I believe that what people want, especially this year, is someone with proven executive experience,” he said, with “the ability to be honest with people and lay out the choices that we have to make as a free people to build a good economy for our kids.”