The Democratic presidential primary thus far has been marked by an endless battle over who’d be the most effective agent of progressive change. Hillary Clinton touts her tenacity, as well as her dealmaking acumen; Bernie Sanders points to the populist clamor in the country as the source of untapped political power; Martin O’Malley cites his record of logging progressive victories ahead of the curve as evidence of his political skill.

That’s not because they have no substantive differences, or because their substantive differences have been glossed over—but those differences are modest enough that they have been subordinated beneath the question of how they’d achieve their goals. 

This sits in stark contrast to the melee underway in the Republican primary, where questions of electability, ideological purity, and the basic shape of the world have blended messily into one another. But while it’s tidier than Republican infighting, the Democrats’ fixation with theories of change is also fairly immaterial to the actual stakes of the 2016 election for Democrats.

Republicans, in a cacophonous and distinctly Republican way, are having the debate Democrats should be having—and vice-versa. The GOP’s lock on the House of Representatives, if not the entire Congress, has sharpened the political stakes for both parties, but in different ways. Both want to nominate electable candidates, of course, but a Republican president in 2017 will have levers of power at his disposal that no Democratic candidate will enjoy. Republicans should thus be placing a premium on selecting a nominee who can best unite the warring factions of their party.

For Democrats, the math is vastly different. If the next president is a Democrat, he or she will be severely encumbered by the GOP’s vise-like grip on Congress. The cardinal imperative of electing a Democrat in 2016 is to prevent Republicans from consolidating control of government and using it to regressive ends. Against that backdrop, the question of who’s best equipped to advance progressive goals fades into near-irrelevance, behind the less-inspiring question of which candidate has the best chance of winning—and the symbolic question of whether Clinton’s gender should override doubts about her progressive bona fides. Is Hillary Clinton the most electable candidate? And even if she is, would her administration recall the ‘90s-era Democratic transgressions against poor and marginalized constituencies so much that it overrides the historic prerogative to elect a female president? 

Saturday’s Democratic debate would be an ideal venue for addressing both questions. They have been sidelined thus far in large part because Sanders and O’Malley have chosen to avoid them. But if they are serious about winning the nomination, and not just about shaping the debate and angling for cabinet positions, they’re making a serious error.

Sanders earned a lot of good will in the first debate by absolving Clinton of Republican attacks on her handling of State Department email. O’Malley has been consistently critical of Clinton not for being unelectable, but, if anything, for thinking too calculatingly about staying electable. “History celebrates profiles in courage, not profiles in convenience,” O’Malley said when Clinton endorsed a right to same-sex marriage earlier this year. 

That’s the wrong approach for a serious candidate in the political climate Democrats face. If either Sanders or O’Malley can mount a convincing argument that Clinton—despite a vast name-recognition advantage, and unique appeal to female voters—isn’t the most electable Democrat, they are doing both themselves and their party a disservice by not airing it. 

The question for both men, then, is whether and why they believe that nominating Clinton puts the country at greater risk of singular Republican control over the government. If they have no answer, both of their candidacies are greatly diminished. And if Clinton can best O’Malley and Sanders on the electability question, or fight them to a draw, subsequent questions become much less tricky for her. If she’s the most electable candidate, her appeal to Democrats is obvious. And if all three candidates are electable, then the argument that Democrats should nominate another male candidate, rather than the first female major-party candidate, becomes a very tough sell. (Point, Hillarybots.)

It’s not an impossible sell. But it would require her opponents to paint a grim picture of a Clinton presidency—one in which she will join coalitions with Republicans to sell out core progressive values, and thus would actually be a relative setback for women and progressives, notwithstanding its watershed nature. (Counterpoint, Berniebros.)

These are uncomfortable questions for all three of the candidates. It’s why the online tussle between Clinton and Sanders supporters has become so ugly. But it’s the debate they should be having.