By Jeremy Diamond

PHILADELPHIA (CNN) — Donald Trump on Thursday offered up his most detailed prescriptions yet to address the student debt crisis, proposing an income-based cap on student loan payments and an ambitious student loan forgiveness program.

Trump, in a meandering speech to a group of rowdy high school and college students, called for a single student loan repayment plan capped at 12.5% of a borrowers’ income and suggested borrowers would see their student debt forgiven after 15 years of making full payments.

“We’re going to work it out. It’ll be a negotiation,” Trump said, prompting one student to shout out “Art of the Deal!”

“We’re going to work it out big league,” Trump added.

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But Trump’s latest and most-detailed proposals on the issue offered little detail as to how much his plan would cost or how he would pay for it. Trump has repeatedly laid out expensive proposals, such as his sweeping tax cuts, while offering few avenues to avoid ballooning the federal debt, which Trump has said he is concerned about.

Trump did not say how the government would pay for forgiving borrowers’ student loan debt after 15 years or for capping student loan repayments at 15% of a borrowers’ income. Trump simply said, “If borrowers work hard and make their full payments for 15 years, we’ll let them get on with their lives.”

The Republican nominee’s campaign did not respond to requests for additional details and offered no additional explanation or supporting evidence, as presidential campaigns traditionally do when unveiling new policy.

Trump has frequently said he is asked about student debt more than any other issue on the campaign trail and has called it a tremendous problem.

Trump, as he has previously, also called for holding universities more accountable on the percentage of their endowment that they spend on administrative costs versus spending that directly impacts students.

“If colleges refuse to take this responsibility seriously, they will be held accountable, including by reconsidering whether those with huge endowments deserve to keep those endowments tax exempt. We have a lot of power over the colleges. And they’re not doing the job of cost cutting,” Trump said.

Throughout his remarks, Trump lamented the skyrocketing cost of education and the mounting total of student debt in the US, which in 2012 topped $1 trillion and has overtaken the amount of car, home and credit card debt in the country.

Trump also said he would “take steps to push colleges to cut the skyrocketing cost of tuition,” but did not lay out those steps beyond leveraging universities’ tax exempt status to seek out concessions on tuition costs.

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Hillary Clinton has laid out a plan to tackle student debt that includes allowing borrowers to refinance their student loan debt and cap their repayments at 10% of borrowers’ income, helping borrowers defaulting on their debt to protect their credit and offering a three-year loan repayment deferment program for entrepreneurs.

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