With Hillary Clinton set to make a major speech on Saturday launching her campaign, there's a lot of interest in what issues she'll build her campaign around. And her campaign has promised that one topic will be a big priority early in her presidential run: student debt.

Now, lawmakers and policy experts on the left are coalescing around a set of solutions that offer a window into the kinds of ideas that Clinton and her staff are sifting through as they fill in the details of her platform.

This week, progressive leader Sen. Elizabeth Warren (D-Mass.) laid out policies to improve college affordability, including making states maintain a minimum level of investment in higher education and pouring more federal dollars into aid programs.

"Our economy cannot flourish if we don’t have enough college-educated workers, but our economy will stagnate if students take on bigger and bigger debt loads to pay for college," Warren said at the Shanker Institute Wednesday.

Some of Warren's ideas, such as forcing colleges to pay up when students default on loans and simplifying the application for federal aid, are tenets of a higher education agenda introduced by Sen. Lamar Alexander (R-Tenn.), the chair of the Senate education committee. She is making a case for bipartisan action, calling on Democrats and Republicans to have the "courage" to "admit how much is wrong and that the other side has a real point."

“We can do it if Republicans admit that we will never have affordable college without investing more resources in education," she said. "And if Democrats admit that we will never have affordable college without demanding real accountability in exchange for those investments.”

Warren has led the charge in promoting college affordability as a major issue in the 2016 presidential race, calling for the elimination of student debt at public colleges. That debt-free college initiative, the brainchild of liberal think tank Demos, has been endorsed by Democratic contenders Sen. Bernie Sanders (I-Vt.) and former Maryland Gov. Martin O'Malley.

Sanders has built on the initiative with his own ambitious plan to make four years of public college free by imposing a tax on transactions by hedge funds, investment houses and other Wall Street firms. The independent senator from Vermont estimates his plan would cost $70 billion a year, making it a political nonstarter among fiscal conservatives.

It's unlikely that Republican presidential candidates will sign onto any plan with the word "free" in it, but GOP contenders are expressing interest in finding ways to tackle the cost of college.

Sen. Lindsey Graham (R-S.C.) and former Arkansas governor Mike Huckabee have said they would support letting borrowers lower the interest rates on their federal student loans. And New Jersey Gov. Chris Christie, Sen. Marco Rubio (Fla.) and former Florida governor Jeb Bush have framed the issue of student debt as a barrier to economic mobility.

While the conservative American Enterprise Institute has proposals that these candidates could use as the basis for their platform, other advocacy groups are presenting ideas in hope that candidates on both sides of the aisle will adopt them.

Young Invincibles, an advocacy group representing millennials, this week released an agenda that touches on some proposals that Republicans have backed, including simplifying education tax credits and financial aid applications to get students the money they need to pay for college. The agenda also calls for tying maximum Pell Grants to the average in-state tuition cost, a proposal that is sure to appeal to Democrats who have been pressing for an expansion of the federal program for years.

Each of the seven reforms are presented as individual proposals, complete with separate price tags, making it ease for candidates to pick and choose what works best for them. All told, the group estimates that adopting the entire platform would take an annual investment of $31.5 billion.

"As you go through the list, there are people in both parties who have supported these ideas," said Aaron Smith, co-founder of Young Invincibles. "If this is going to happen in a real legislative way, it will require actual dollars."

Want to read more on paying for college? Check out these stories: