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If you thought the last few Democratic primary debates were a train wreck—too many candidates onstage, moderators asking the same questions (about, say, Medicare for All) over and over—the next one, on October 15, promises to be even worse. Twelve contenders will face off, the most ever to share a single stage in a primary debate. And with the Ukraine scandal dominating the news, the moderators will be tempted to bombard the candidates with questions about impeaching Trump that are more or less irrelevant to the duties of the next president, should one of them get the job.

But the moderators—Erin Burnett and Anderson Cooper of CNN and Marc Lacey of The New York Times—have some power to make the event at least a little less awful by raising issues that matter to voters but haven’t gotten the airing they deserve. They can ask questions about specific policies that address those issues that some candidates have advocated, and others have not. This would at least make the evening a little more informative, and possibly even livelier.

One issue begging for more discussion is the alarming state of America’s democracy and electoral infrastructure. Democrats can propose all the shiny new policies they want, but few will ever become reality unless the party can notch decisive victories in Congress—as well as in state legislatures and governor’s mansions, which control the redistricting process. That, in turn, will require solving the problem at the root of Democrats’ recent struggles: while their agenda is broadly more popular than the other side’s, the groups that most support them—especially young people and minorities—don’t turn out to vote as much as older, whiter, more conservative voters.

As it happens, two of the candidates who will be onstage—Elizabeth Warren and Cory Booker—support what could be the single most efficient policy to not only reverse this trend, but to patch up our frighteningly insecure election system: universal vote by mail, otherwise known as “vote at home.”

So here’s a suggestion for the moderators: ask Warren and Booker to explain their proposals to expand voting by mail, and ask the other candidates, especially Joe Biden and Bernie Sanders, why they don’t agree—or if they do, why they’ve been silent on the idea.

Instead of going to a polling place and casting a ballot the old-fashioned way, universal vote by mail allows people to receive their ballot in the mail a few weeks before election day, and then have the option to either mail it in or drop it off at a secure site. It’s a system now being used in Oregon, Colorado, Utah, and Washington, and soon in Hawaii. It’s been getting results. In the 2018 midterms, for instance, every vote at home state had a turnout rate at least 10 percentage points higher than the national average.

There’s nothing inherently partisan about vote at home’s benefits. Because it actually saves money that would otherwise go to staffing in-person polling sites, some of its biggest champions have been Republican officials in rural counties. The Pew Research Center found that, since 2014, Colorado has saved $6 per voter per election.

That helps explain why Utah, a deeply red state, has been embracing vote at home. Last year, a study commissioned by the Washington Monthly found that Utah counties that enacted vote at home for the 2016 election had a voter turnout rate of 5.2 percentage points higher than those that didn’t.

Still, the issue has tended to face a partisan log jam. Republican leaders worry that the increased turnout caused by vote at home would benefit Democrats. They’re not crazy to think so: the effects are most pronounced among young voters, precisely the group the Democratic Party needs most to turn out. In 2014, Colorado voters in the 18-to-24-years-old bracket turned out 12 percentage points higher than was forecast by a generally accurate turnout model; 25-to-34-year-olds outperformed expectations by 7.4 percentage points. And that was in a midterm election that had the lowest voting rates for an American election cycle in 70 years.

Spreading vote at home would thus help make the American electorate look more like the American population overall. In the short term, that would probably be a good thing for Democrats. In the long term, it would be a good thing for democracy, because it would put pressure on both parties to cater to a broader swath of the public, not just the aging Baby Boomer crowd.

All in all, vote at home has so far proven itself to be both more promising and more cost effective than many of the alternative proposals to increase voter turnout. (Automatic voter registration, arguably the buzziest proposal, is a great idea—but it doesn’t solve the problem of turning non-voters into voters.) If any of the Democrats vying for the nomination want to restore a functioning American democracy—and turn their policy ideas into law—it’s the first place they should start. And if they disagree, they should explain why.