Secretary of State Maggie Toulouse Oliver and New Mexico Democrats recently introduced a plan to automatically register every eligible voter when they obtain a driver’s license, unless they affirmatively opt out. Despite Democratic majorities in both state legislative chambers, the bill nonetheless died in committee last Thursday when Democratic state Reps. Debbie Rodella and Daymon Ely stunningly sided with Republicans to block it.

This proposal always faced the possibility of a veto threat from Republican Gov. Susana Martinez, but that was no excuse whatsoever for Democrats to thwart it. That’s particularly so because Martinez is term-limited in 2018, and Democrats have a strong chance to regain the governor’s office next year. If they’re successful, they could then reintroduce their automatic registration bill—but only if wayward Democrats themselves don’t inexplicably stand in the way.

Registration has long been a barrier to participation in the electoral process. The proposal before the New Mexico legislature isn’t perfect, but it would go a long way toward expanding the electorate. When Republican legislators in state after state propose bills that make it harder to vote, Democrats have to do everything they can to ensure that citizens can exercise their most fundamental political right with ease.

Expanding voting rights should be one of the first things on the Democratic agenda when Republicans can’t stand in the way, but it’s simply impossible when members of our own party won’t even hold together. Democratic legislators who won’t support strengthening voting rights need to hear from their constituents. If they don’t change their minds, they must be held accountable.