Former Maryland governor Martin O'Malley with his wife, Catherine Curran O'Malley, as he announced his candidacy  May 30. (Jabin Botsford/The Washington Post)

This post has been updated.

Democratic presidential hopeful Martin O’Malley on Wednesday put forward an ambitious five-year goal of allowing students to graduate debt-free from public colleges and universities across the country.

The proposition is deeply personal for O’Malley: Aides say he and his wife have already incurred $339,200 in loans to put the two eldest of their four children through universities. And college affordability was a leading priority for O’Malley during his tenure as Maryland’s governor.

The issue is one being talked about a lot these days by Democrats, including the party’s other White House candidates, as more and more students enter the workforce with hefty debt loads.

[Sanders, O’Malley race to be the Clinton alternative]

O’Malley, who detailed his plan during a morning event in New Hampshire, called on states to freeze tuition rates at public colleges and universities  -- as Maryland did for four years -- and proposed other measures that would help those carrying debt.

Under O’Malley’s plan, students and parents would be able to refinance their debt at lower interest rates. And O’Malley would base the repayment terms for student borrowers on their income upon graduation.

For the long term, O’Malley said he would set a goal of limiting college tuition to 10 percent of a state’s median income at four-year institutions and 5 percent at two-year institutions. Federal matching grants would help states that participate in reaching the goal.

Under his plan, O’Malley would also increase Pell Grants and revamp federal work-study programs to help cover non-tuition costs, such as room and board.

“Right now, student loan debt is holding us back -- student by student, family by family, and as a nation, we have to do better," O'Malley said during an event at Saint Anselm College in Manchester.

Aides declined to spell out the cost of O’Malley’s initiatives but suggested they could be paid for by measures such as closing corporate tax loopholes and taxing capital gains at the same rate as earned income.

Sen. Bernie Sanders (I-Vt.), who’s emerged as the leading alternative for the Democratic nomination to Hillary Rodham Clinton, has proposed a somewhat different idea: making four-year public colleges and universities free. His plan, which he estimates would cost $70 billion a year, would be paid for in part by a tax on Wall Street transactions by investment houses, hedge funds and other speculators.

[In Bernie Sanders, an unlikely — but real — threat to Hillary Clinton]

Clinton is also expected to detail college affordability plans in coming weeks.

O'Malley's plan prompted some back and forth on the campaign trail Wednesday, with Republican contender Jeb Bush characterizing O'Malley's plan as "more free stuff" during a stop in Dover, N.H.

O'Malley shot back later in the afternoon, saying in a statement that "debt-free college isn't about 'free stuff.' It's about providing opportunity to every American."

In recent years, O’Malley’s daughter Grace, 24, graduated from Georgetown University, and another daughter, Tara, 23, graduated from College of Charleston. (Georgetown is a private university, while College of Charleston is a public university in South Carolina.) Aides said O’Malley and his wife, a district court judge in Baltimore, have taken out nine loans totaling $339,200 to help pay for the education of their oldest two children. The interest rates range from just over 6 percent to 8.5 percent, an aide said.

While some provisions in O’Malley’s plan would not affect private universities, O’Malley aides said those schools would have an incentive to keep costs down as public colleges and universities become more affordable.

In an e-mail sent to O’Malley supporters  Tuesday, Grace O’Malley, now a public school teacher in Baltimore, relayed her college-tuition story and urged others to do so on a Web page set up by her father’s campaign.

“I had to make a tough choice: Do I go to the college we can afford or do I take out loans to go to the college of my dreams?” she wrote. “At the age of 18, I made the decision to follow my dreams. My family and I now face years of debt -- and we know we're not the only ones.”

NH1 Political Director Paul Steinhauser in Dover, N.H., contributed to this report.