President Obama on Thursday proposed free tuition for students to attend two years of community college. The White House, which estimates that 9 million people a year could benefit from the program, says it wants community college to be as "free and universal" as high school.

But there's a major catch (aside from just the fact that a Republican-led Congress is unlikely to sign off). Free tuition, even for two years, is not nearly enough to cover the cost of attending college.

Tuition and fees counted for just 21 percent of the budget for students who attend two-year public college and pay for off-campus housing, according to a recent study from College Board. While the average tuition and fees at a community college is $3,347 for the 2014-2015 academic year, housing cost another $7,705, books averaged $1,328 and transportation added up to $1,735. Keep in mind, too, that Obama's plan also doesn't cover fees, which schools routinely charge for using labs, campus health centers and computer labs.

Four-year colleges cost much more than community college, but tuition at these schools also cover a much bigger portion of the cost, as you can see below.

Students at community colleges could save money on housing by living at home, but that's not an option available to everyone. There is also a good chance that low-income students could qualify for federal Pell Grants that would cover whatever is left over after the government pays tuition, but again not everyone is eligible. Many students could still wind up working full time or taking out loans, albeit smaller amounts, to pay the difference.

Higher education scholar Sara Goldrick-Rab at the University of Wisconsin-Madison has looked at ways to divvy up costs between the federal and state government to save students the headache of covering fees, books and supplies. In a recent research paper, she proposed having the federal government provide grants to schools to cover two years of tuition and states redirect higher ed funding to cover books and supplies. Living expenses, she said, could be covered through 15 hours a week of state or federal work study at a living wage.

Goldrick-Rab said the government could pay for universal community college by redirecting all existing federal higher education grants, tax breaks and workforce training money at a total budget of $85 billion. Individually those programs only benefit segments of the population, but shifting the money to cover free tuition for all would go further to broaden access to education.

Some students would still have to borrow to cover any additional living expenses under this plan, but it could be a smaller population than under the White House program. Either initiative would require a significant investment in the infrastructure of community colleges, including more faculty and staff to deal with an influx of students. Four-year public colleges would also have to do a better job of accepting transfer credits to make sure students graduating from community college have a seamless transition.

And there's another reason Obama's plan will be tough to implement. Getting states to invest in higher education could be a major hurdle, especially after years of divestment in the wake of the recession. Obama's plan calls on states to pick up about a quarter of the cost of the program, while the federal government would foot the rest of the bill. That sort of cost-sharing deal could work for states, like Tennessee, that already have initiatives to reduce the cost of college.

Obama's plan is loosely modeled after the Tennessee Promise, a program that uses state lottery funds to pay tuition at community colleges that is not covered by public grants. Just like the White House plan, the Tennessee Promise fails to address all of the other expenses students incur attending college.

Yet at a time when students are graduating college with an average $28,000 in debt, it's hard to argue against any plan that could reduce the need for student loans. It's something. But it's still not the panacea that students have been waiting for.