A college education is a basic requirement for many middle-class jobs, but it is increasingly harder to afford. That is why every presidential candidate needs to explain what he or she will do to make higher education attainable for more Americans without them having to take on crippling amounts of debt.

On Monday, Hillary Rodham Clinton, the Democratic front-runner, released an ambitious proposal that aims to help students at public four-year colleges graduate without incurring any debt for tuition. Bernie Sanders, a senator from Vermont who is also seeking the nomination, has gone even further and said that he would make tuition free for all undergraduate students at public institutions. Regrettably, none of the Republican candidates have come up with anything comparable.

Students and their families are paying more for college and going deeper into debt every year. About 60 percent of graduates from four-year public universities had student loans in 2013. On average, they owed $25,600, up 20 percent from 2000 after adjusting for inflation, according to the College Board. They are paying more in large part because state governments reduced higher education spending by 25 percent per student between 2000 and 2014 in inflation-adjusted dollars, according to the State Higher Education Executive Officers Association. More than 11 percent of total outstanding loans are delinquent by more than 90 days compared with 6 percent in 2005, according to the Federal Reserve Bank of New York.

Mrs. Clinton’s plan aims to reduce college costs for students by giving federal grants to states and colleges and by allowing borrowers to refinance their student loans at lower interest rates. It would reward states that agree to spend more money on higher education and give more money to colleges that reduce expenses, though it does not say what kind of costs should be lowered. It also includes a good proposal put forward by President Obama in January to make two-year community colleges free to all Americans. The plan would cost $350 billion over 10 years, which is close to what the federal government currently spends on Pell Grants. Those grants will continue. Ms. Clinton would raise the money by capping unspecified deductions wealthy families can take on their income taxes.