"The Pay It Forward structure does nothing to address tuition levels or college costs for students, nor does it adequately address funding for the instruction, research, and robust student support services that are the hallmark of a high quality college education," said a coalition of higher education groups in an October statement. "Furthermore, it would diminish the power of middle- and working-class families’ to put pressure on politicians and colleges to keep costs down."

And unlike federal loans that treat students equally – regardless of their intended majors, the type of institution he or she is attending or the student's academic record – opponents have said private student investment plans could take those factors into account and may therefore be less available to students with more "high-risk" majors that are known to not be as lucrative.

Still, Rubio said such a plan would encourage a "free enterprise system" and allow "people to access the skills needed to take advantage of the opportunities created by the free market."

"Fostering more choice for students to fund their education guarantees opportunity and equips people with the tools needed to achieve the American dream," Rubio said.