Same-day voter registration is a fine idea. But it’s a bad provision to include as a mandatory requirement to be imposed on states in the federal voting rights bill unveiled by Senate Democrats last week.

Currently, less than half the states permit same-day registration, which allows voters to register when they cast ballots on Election Day or during early voting. The majority of states impose the traditional requirement that voters register in advance. Among these traditional states are Massachusetts, Rhode Island, New Jersey and Delaware — not ones in the news for recent “voter suppression” laws.

Is same-day registration sound policy? Yes. It makes voting more accessible. Specifically, it enables citizens who wait to the last minute before deciding to cast a ballot to participate in the election, and as a procrastinator myself, I’m sympathetic to giving people every opportunity to participate in collective self-government. As a form of one-stop shopping, it also makes fulfilling the civic function of democracy much more convenient: Who wants to make two trips to the election administration storefront, so to speak, when one would suffice?

But is same-day registration an essential element of a fair voting process? I can’t say that, and in a federalist system each state should get to make this choice on how best to run its democracy.

And the risk of including nationwide mandatory same-day voter registration in the Democrats’ proposal is significant, because the requirement is so polarizing. Republicans have opposed this idea for years, believing it insufficiently attentive to election security. The fear is that unregistered voters will show up at one polling place on Election Day, register and cast their ballots on the spot, and then do the same at another polling place later the same day, their second invalid ballots already irretrievably comingled with the rest of ballots to be counted when the polls close.

This risk, while theoretical, is not unduly worrisome as a practical matter, especially given the new technology of electronic pollbooks, which can update statewide registration databases instantaneously and prevent that second attempt to register and vote.

But even if GOP opposition to same-day registration is overblown, putting it in the Senate package makes it even harder than it already is to achieve any semblance of bipartisanship. It is, in short, guaranteed to make it easier for Minority Leader Mitch McConnell (R-Ky.) to keep his Republican caucus lined up in opposition to the bill.

That has costs — even if Democrats somehow manage to find a way around the filibuster and pass the bill with only Democratic votes. It would increase, not decrease, the risk of losing democracy in the next few years, by making it more likely that Republicans would repudiate an electoral defeat, especially on Jan. 6, 2025.

“You can’t trust an outcome produced by same-day registration,” they would say — and there would be more of them saying it than if Congress hadn’t forced all states to adopt this policy. Responsible Republicans such as Rep. Liz Cheney (R-Wyo.) would have a harder time persuading GOP colleagues to accept a loss at the polls.

Thus, if the goal is to reduce the risk that Republicans will negate the will of the voters in upcoming elections, attempting to enact same-day registration without Republican support seems exactly backward.

But more worrisome than Democrats getting it enacted is that its inclusion in the bill will block adoption of what’s truly needed, such as measures to prevent ballot-tampering and phony audits of the kind Arizona and other states have been pursuing. The new bill appropriately contains provisions on these crucial points, but without a filibuster miracle they don’t stand a chance as long as they are attached to one-sided dealbreakers.

The new bill also bans partisan gerrymanders, a provision that truly is essential to protect democracy. Some might question that assertion, given that gerrymanders have existed since Elbridge Gerry’s salamander-shaped map in 1812. Computer-generated gerrymanders, however, are far more effective today in subverting the will of the voters than Gerry’s redistricting.

What is worse, a gerrymandered Congress is more likely to subvert the 2024 presidential election than a Congress elected using fairly drawn districts. This is true not only because gerrymandered maps produce more extremist representatives, but also because gerrymandering engenders a mind-set that the partisan pursuit of power is just fine regardless of what voters want.

Anyone worried about this, and we all should be, needs to evaluate carefully what Congress should — and should not — do now to mitigate these threats. Some steps that Congress is contemplating might make matters worse if adopted, and including them within a proposed package might prevent enactment of measures that should be the true priorities for protecting democracy.