Nine additional Democratic senators on Wednesday came out in support of a resolution calling for debt-free public college, bringing to 20 the total number of Senate Dems who support the measure, introduced only a month ago by Sens. Elizabeth Warren (D-Mass), Brian Schatz (D-Hawaii), and Chuck Schumer (D-N.Y.).

The resolution  calls on federal and state governments, along with higher education institutions, to work in concert to lower tuition costs, increase financial aid, and reduce the burden of existing student debt.

As described by The Hill:

The resolution deals in broad strokes rather than granular details. It calls upon the federal government to provide more support to states, which can then “make increased investments in higher education that will result in lower tuition and costs for students.” It also backs increased financial aid for students—in contrast to the House GOP’s recent budget plan that would freeze Pell grants at their current level—as well as efforts to bend the cost curve of college education downward.

“A student at a public university today faces tuition prices that are more than 300 percent of what his or her parents faced just 30 years ago, and total outstanding student loan debt now stands at a staggering $1.3 trillion,” Warren said upon introducing the proposal. “Our country should be investing in higher education and working with colleges and universities to bring down tuition costs so that students don’t have to take on crushing debt to get an education.”

Wednesday’s news—combined with the elevation of Democratic presidential candidate Bernie Sanders’s call for tuition-free higher education—lends further credence to recent claims that, as the Washington Post put it on Saturday, “the $1.3 trillion burden of student debt is becoming an issue in the 2016 presidential campaign.”

The Guardian wrote on Wednesday that increased support for the Democrats’ plan “adds pressure on potential 2016 Democratic presidential candidates to either endorse the resolution or come up with a plan of their own, with supporters of the debt-free college measure particularly interested in seeing where Hillary Clinton will come out on the issue.”

As Adam Green of the Progressive Change Campaign Committee (PCCC), one of the liberal groups driving support for the measure, told The Hill: “[T]he beauty of debt-free college is that it is a game-changing policy in millions of people’s lives and it is a tremendous winner for Democrats with voters. Our goal is to have it be a central campaign issue in 2016. When voters go to the polling booth, we want them to be thinking about debt-free college as one of the main things.”

And many of them will be.

Democratic pollster Geoff Garin, who worked on Clinton’s 2008 campaign, told the Washington Post he thinks the issue of student debt is “as important to millennials as ‘war and peace issues’ were to baby boomers.”

“A part of the reason student debt is so important for Democrats is that it’s a crucial motivator to get younger people to vote,” Garin told the Post. “Student debt is often the defining economic fact of their lives.”

According to The Hill, the nine Democrats who announced their support for the measure Wednesday are Sens. Richard Blumenthal (Conn.), Barbara Boxer (Calif.), Al Franken (Minn.), Kirsten Gillibrand (N.Y.), Mazie Hirono (Hawaii), Ed Markey (Mass.), Gary Peters (Mich.), Jeanne Shaheen (N.H.) and Debbie Stabenow (Mich.).

Reps. Keith Ellison (D-Minn.), Raul Grijalva (D-Ariz.), and Katherine Clark (D-Mass.) have introduced a version of the bill in the U.S. House.