Hillary Clinton announced her new higher education plan this summer with a burst of fanfare, promising to invest $500 billion to eliminate tuition for millions of students at public colleges and universities across the country. The move was an expansion of an earlier, less ambitious proposal, and was seen as a conciliatory gesture to her left-leaning primary opponent, Senator Bernie Sanders of Vermont, and his supporters ahead of the Democratic Party’s convention.

“One of the biggest issues that I hear about throughout the campaign, that I hear about from every corner of our country, is how much an education costs,” Mrs. Clinton said Wednesday at a campaign event in New Hampshire with Mr. Sanders. “Bernie’s absolutely right.”

But while the liberal wing of the party has cheered the idea as a needed antidote to soaring tuition and student loan debt, many in education have questioned how such a plan would work. More government influence in the sector could lead to unintended consequences, they fear, and some details of Mrs. Clinton’s proposal remain murky.

“We appreciate that Mrs. Clinton understands that states are disinvesting from higher education in their states,” said Peter McPherson, the president of the Association of Public and Land-grant Universities, who expressed approval that a candidate was trying to broaden access to higher education in a bold way. “But her plan at this juncture doesn’t fill out the details.”