Democratic presidential candidate Elizabeth Warren lashed out at billionaire Leon Cooperman on Monday for his stake in student loan servicer Navient and stressed the importance of forgiving student debt.

"I care about an entire generation of students being crushed by student loan debt — deferring their American dream because they can't afford it," Warren, the senior senator for Massachusetts, wrote in a Tweet. "I'm not afraid to stand up to the wealthy and well-connected."

tweet 2

Navient is being sued by several states for misleading borrowers. An audit by the U.S. Department of Education last year suggested the company uses deceptive practices.

Outstanding education debt has outpaced credit card and auto debt, and the average college graduate leaves school $30,000 in the red today, up from $10,000 in the 1990s. Default rates are on the rise, and a senior student loan official recently resigned from the Trump administration, calling its lending system "predatory" and "unsustainable."

Warren plans to pay for her student debt forgiveness plan with a 2% annual levy on accumulations of wealth exceeding $50 million, and an additional 6% tax on wealth over $1 billion.