Where the 2016 Democratic candidates stand on college affordability

The total student loan debt held by Americans is estimated to be over $1.3 trillion dollars, surpassing even total credit card debt as the largest source of household debt in the country.

To make matters worse, the average cost of a college education has risen sharply in recent years, thanks in large part to the state budget crunches that followed the recession and the 2008 financial crisis. The numbers are striking: A report earlier this year from the left-leaning Center on Budget and Policy Priorities found that average annual tuition at public colleges and universities in the U.S. increased by 29 percent between 2008 and 2015. Some states saw tuition increases of over 60 percent.

The Democrats running for president - Hillary Clinton, Bernie Sanders, and Martin O'Malley - have argued that the soaring cost of a college education not only drags on the economy by forcing young workers to pay off debt instead of consuming, it also betrays the American dream by pushing a college degree out of reach for the less affluent.

Identifying the best way to fix the situation, though, depends on which candidate you ask. From reducing the cost of college to providing relief to people currently holding debt, here's a look at the candidates' proposals.

Hillary Clinton

Hillary Clinton's "New College Compact" is a $350 billion college tuition plan that aims to enable students to attend a four-year public college without taking out loans for tuition. Community college would be tuition-free.

She would institute a $200 billion federal incentive system to give grants to states that promise to offer no-loan tuition at four-year public colleges and universities, and free community college tuition.

"We need to make a quality education affordable and available to anyone who is willing to work for it -- without saddling them with decades of debt," Clinton said when she unveiled the plan in August.

Clinton's plan would require students to work 10 hours per week and contribute their wages to their education. And students' families would also be required to contribute. "I think it's important for everybody to have some part of getting this accomplished," she said during the first Democratic debate last month. "That's why I call it a compact."

To reduce the burden on people currently saddled with student debt, Clinton would allow them to refinance their loans at lower rates. She would also expand programs that calculate monthly loan payments based on a person's income, and she's said that nobody should have to fork over more than 10 percent of their income to repay student loans.

Clinton says her plan would be fully paid for by limiting the tax deductions wealthy Americans are allowed to claim, effectively raising taxes on high-income households.

Bernie Sanders

Bernie Sanders would go a step further than Clinton: rather than aiming to eliminate the need for students to take out loans to pay tuition, he would eliminate tuition at public colleges and universities altogether. As a senator, he's offered a bill to accomplish this plan.

"This is not a radical idea," Sanders' campaign website declares, citing countries like Germany and Sweden that have taken similar steps. "If other countries can take this action, so can the United States of America. In fact, it's what many of our colleges and universities used to do."

And he's said colleges and universities must cover 100 percent of the "financial needs" of lower-income students by allowing them to spend financial aid on living expenses like books and housing.

He's criticized Clinton's plan, with its incentive programs and work requirements, as too cumbersome.

"I don't think we need a complicated system, which the secretary is talking about...the income goes down, if you're poor you have to work, and so forth," he said last month at the first Democratic debate.

Sanders, like Clinton, would allow people currently repaying their loans to refinance their debt. And he would reduce interest rates, according to his website, by resetting the formula for calculating student loan interest rates "back to where it was in 2006. If this plan were in effect today, interest rates on undergraduate loans would drop from 4.29% to just 2.37%."

To pay for his plan, Sanders would impose a tax on high-speed trading and other forms of what he's described as Wall Street speculation, and he would slash defense spending.

Martin O'Malley

Martin O'Malley, like Clinton, would aim to reduce the cost of tuition and eliminate the need for students to borrow money, rather than eliminating tuition at public colleges as Sanders proposes.

He's outlined a proposal that aims to ensure any student can access a debt-free college education at any in-state university within five years. His plan calls on states to immediately freeze tuition rates - something he did for four years as governor of Maryland, his website notes - and it urges states to undo recent cuts to higher education funding by "leveraging federal dollars through matching grants."

Tuition at public four-year colleges would be limited to no more than 10 percent of a state's median personal income, and it would limit tuition at two-year institutions to no more than 5 percent. He would also expand Pell Grants and work-study programs.

Like Clinton and Sanders, O'Malley would allow current student debt-holders to refinance, and he'd limit monthly loan payments based on income.

So what's the problem?

Free college sounds like a commendable goal, some Republicans have said - but who's going to pay for it?

GOP presidential candidate Marco Rubio, in an interview with Fox News in August, said of Clinton's college plan, "She has to figure out who to raise taxes on - so this is about making doing business in America even more expensive - raising taxes, and then taking all that money and pouring it into an outdated higher education system."

Other Republicans have opposed the very idea of giving away a college education for free, arguing that students need to have some skin in the game.

"[I]f college graduates are going to reap the greater economic rewards and opportunities of earning a degree, then it seems fair for them to support the cost of the education they're receiving," Chris Christie, also a GOP presidential candidate, said in June. "Earning a degree should actually involve earning it."

Given the GOP's philosophical objections, all three Democrats can expect to be pressed on how they hope to enact their plans for debt-free college in a combative political environment. Some proposals could be instituted unilaterally, but others, like allowing people repaying their loans to refinance or eliminating college tuition altogether, would require an act of Congress. And that will be hard to secure if Republicans maintain their grip on at least one chamber.

Ditto for Clinton's and Sanders' plan to hike taxes to pay for their proposals - is it realistic to believe Republicans would ever support such measures?