NEW YORK (MainStreet) — If Baby Boomers and the younger contingent of Millennials—the 18-to-24 crowd--were lumped together, they’d be roughly one-third of the U.S. population. Boomers comprise 76.4 million people with the 18-24 Millennials making up 31.4 million—about 107 million people out of some 310 million. That's are also where the student loan crisis is located, either as borrowers or, in the case of Boomers, loan co-signers and borrowers.

These loans have taken a toll. Millennials can’t afford to buy real estate. Boomers get whacked in retirement.

Taken together, they represent a lot of voters--ones 2016 presidential hopefuls can't ignore. Meanwhile, student loans account for over 35% of all consumer credit and 14% of all student loans are in default. So when it comes to the candidates, what have they done and where do they stand on student loans?

Democrat hopeful Martin O’Malley froze tuition at state schools for four years as governor of Maryland and supported the Obama Income Based Repayment Act of 2010. Independent Vermont Senator Bernie Sanders, who is also seeking the Democratic nomination, wants to pass a law that will help students earn college credits in high school to reduce the cost of earning a college diploma. Like Senator Elizabeth Warren (D-Mass.), who has famously spurned calls to run, Sanders wants to lower interest rates on student loans.

Of the 14 announced Republican hopefuls, Jeb Bush, former Governor of Florida, champions Massive Open Online Courses (MOOCs) and for-profit colleges, and he has criticized the Obama administration's treatment of these institutions as being too harsh, while many believe that, until recently, the Department of Education handled most with kids' gloves.

Bush's ties to the for-profit college industry is not a secret. He co-authored an Inside Higher Education article with Randy Best, the chairman for the for-profit online college firm Academic Partnerships, that advocates for online degree programs and an international student body that would keep costs low and eliminate student-instructor face time. Bush was a senior advisor to Best's company until 2014, when he resigned from all board positions. Both Bush and Clinton spoke at a Dallas conference called The Globalization of Higher Education in 2014, hosted by Bush and former North Carolina Governor Jim Hunt. Bush’s advocacy for for-profit colleges, known for their high tuition, seems to be at odds with reducing the need for federal student loans, which the for-profits couldn't function without.

Senator Marco Rubio (R-Fla.) was still paying off between $100,000 and $250,000 in Sallie Mae law school loans when elected to the Senate in 2010, according to a 2011 financial disclosure filing. Last year, Rubio and Senator Mark Warner (D-Va.) introduced a bill designed to consolidate and improve income based repayment options for federal loans. Rubio has also lobbied for the now-bankrupt Corinthian Colleges.

Union-busting populist Scott Walker, Republican Governor of Wisconsin, took the wraps off $300 million in state funding cuts to the University of Wisconsin in February. Walker, who never finished his undergraduate degree, would let the UW system sock students with unlimited tuition hikes. The non-partisan Legislative Fiscal Bureau found that tuition would jump 40% if unlimited tuition increases were used to close Wisconsin’s $300 million funding gap.

Senator Rand Paul’s stance on student debt garnered attention when he announced in April that he wanted all college tuition to be tax deductible. Even if that were a boon for students, the Kentucky Republican’s proposal would lead to a tax hike, something that flies in the face of his anti-tax, anti-Big Government orthodoxy. The term tax deductible turns heads, but these deductions won't lower tuition, which is where the trouble starts in terms of spiking loan balances. Paul has argued against education subsidies and in favor of cuts to Pell Grants, a means-tested fund for low-income students.

Like Marco Rubio, Texas Senator Ted Cruz had student loans but takes a let-em-eat-cake approach when it comes to providing help for others. His defeated 2013 budget amendment would have cut Pell Grants and increased the monthly payments on student loans. Cruz voted to block Elizabeth Warren’s 2014 bill that would have allowed students to refinance their loans at lower rates.

Back-of-the-pack GOP wannabes Ben Carson, Chris Christie, Carly Fiorina, Bob Graham, Bobby Jindal, John Kasich, Rick Perry and Rick Santorum are unlikely to wield influence on student loans as a national issue. Collectively, these eight candidates have the support of 19% of voters polled by Real Clear Politics.

--Written by John Sandman for MainStreet