When Democratic presidential nominee Hillary Clinton presented her plan to make tuition at public colleges and universities free over the summer, it garnered considerable praise from the left, but some aspects of the plan have academics questioning the details left out.

The plan closely mirrors Sen. Bernie Sanders’ (D-VT) vision for debt-free college but with some minor changes, such as who can access the free tuition. By 2021, the plan would allow for students from families who make less than $125,000 to go to a public college or university tuition-free.

“One of the biggest issues I heard about throughout the campaign that I hear about from every corner of our country is how much an education costs,” Clinton said at a New Hampshire rally on Sept. 28. “Bernie Sanders was absolutely right.”

Republican presidential candidate Donald Trump’s plans for higher education are less clear, as he has not released a detailed outline similar to Clinton’s.

Sam Clovis, national co-chair and senior policy advisor of Trump’s campaign, talked to Inside Higher Ed in May, decouncing Clinton’s higher education plans and emphasized moving the federal student loan system out of the government and to private banks.

Clovis did not address cost of tuition or student debt, which Clinton’s plans aim to tackle.

Richard J. Reddick, assistant vice president of research and policy in the UT department of educational administration, said he has looked at economic forecasts and believes the plan can be implemented but some details of the plan still remain unclear to him.

One issue he had was the possibility of the threshold not being implemented correctly because of the varying costs of living in the U.S.

“$85,000 in Mississippi compared to $85,000 in New York City are completely different things, so without some kind of way to adjust or consider cost of living it’s a little concerning,” Reddick said.

Reddick also questioned whether the $125,000 threshold would hold once 2021 comes around.

Another issue Reddick will monitor is the possibility of rising tuition costs. Reddick said states typically fund higher education, and in the last 35 years, the percentage of higher education budgets coming from legislative appropriations have declined.

The funding, which is no longer coming from the state government, is drawn from student tuition costs. Reddick said a possible solution to rising tuition costs is requiring states to distribute money from the federal government.

A study from the Center on Education and the Workforce at Georgetown University estimated a median projected increase in enrollment of 16 percent at public colleges and universities. According to the study, this would lead to a more selective application process at flagship universities, causing a “cascading effect as students who could not get admitted to more selective flagship and mid-tier public universities choose to go to open-access institutions.”

“One issue is whether the Clinton free college initiative would overcome the deeper information barriers to college enrollment and completion,” the study said. “At this juncture the Clinton proposal is too sketchy to address the core findings on the negative effect of information barriers to enrollment.”

José Luis Santos, vice president of higher education policy and practice at The Education Trust, said his organization was pleased someone of Clinton’s status was addressing a pressing issue to students all over the nation, Santos said the plan lacks a detailed approach to increasing college completion rates.

“If she pursues this plan, she should consider the college completion issue as part of platform,” Santos said. “We have a complex problem [in the completion rate] and we need a more comprehensive set of solutions. The federal government needs to invest dollars to states and states need to invest dollars into colleges and universities. Good federal policy can incentivize states to invest more.”