Democrats and Republicans are pressing sharply different arguments on a federal voter-identification bill as debate continues on the Senate floor, with Republicans framing the issue as basic proof-of-eligibility and Democrats arguing the bill’s standards are too strict. Republicans have tried to reduce the dispute to a simple question: if people show identification for other services, Republicans say they should show proof to vote.

In interviews and remarks as the Senate considers the Safeguard American Voter Eligibility Act—referred to in the chamber as the SAVE America Act or SAVE Act—Republican leaders have argued that Democrats are resisting voter ID because of what they believe illegal voting data would suggest. Majority Leader John Thune, for instance, said, “It kind of feels like the only Americans not to support voter ID requirements are Democrats here in Congress,” adding that Democrats either oppose it because it is a Republican proposal, or because they “believe that there are in fact people out there voting illegally and that it’s benefiting Democrats.”

Schumer, the top Senate Democrat, rejected the premise that Democrats oppose voter identification itself, and instead tied his resistance to the bill’s broader structure. When asked about possible negotiation, Schumer said, “Our objection as Democrats is not to a photo ID,” and that “Our objection is that it’s a voter suppression bill.” He also indicated the practical concerns for Democrats center on changes in voter registration requirements included in the legislation.

The bill would require voters to show specified forms of identification at the polls—rules that Democrats argue would effectively require citizenship proof because many common photo IDs do not establish citizenship. In particular, the legislation would require voters who want to register to appear in person at an election office with documents such as a passport or birth certificate, or other approved documentation. Democrats also argue the measure would increase the likelihood that voters could be removed from the rolls and told they are ineligible at voting time.

Schumer said the result could be that “People could show up at the polls and be told, ‘You’re off the rolls,’” describing how verification rules could play out for voters who lack the specific documentation that the bill requires. Even as he said he could support voter identification, Schumer did not give details on what he would accept, responding to a question about negotiating with Republicans by saying, “You’d have to define it clearly and properly and easily.”

Republicans, while acknowledging the argument will turn on how strict the identification requirement should be, have said illegal voting by noncitizens is a key concern they want to address with new federal rules. During floor debate, Wisconsin Sen. Ron Johnson said the SAVE Act “is going to make it harder to cheat, because Americans do not want their legitimate vote canceled by a fraudulent one.” Johnson’s argument emphasizes preventing cancellation of votes, while Democrats have argued that the existing level of noncitizen voting fraud is limited and that the practical burdens of the bill could harm eligible voters.

Supporters also point to the fact that many states already require some form of identification at the polls. The National Conference of State Legislatures reports that 36 states have an ID requirement, with 23 requiring photo identification and 13 accepting non-photo identification, according to the AP account cited in this debate. But Democrats argue the SAVE Act would go further by demanding photo identification and potentially overriding other state-approved forms of ID, including some non-traditional options.

Democrats’ concerns extend beyond in-person voting to the rules that would apply to mail ballots. Under the SAVE Act approach described during debate, people voting by mail would have to include a photocopy of their ID with their ballot, a change Democrats say could create new processing problems in states that are not set up to review and handle photocopies. Virginia Sen. Tim Kaine, a Democrat, said he supports voter ID laws in Virginia that are less strict than the federal requirements and asked why a single federal solution is needed when many states already require some form of ID.

Other Democrats made arguments that the country does not have the kind of noncitizen-voting problem that would justify sweeping federal identification rules. Maryland Sen. Chris Van Hollen said, “If there really were proof of an epidemic of noncitizen voting, we would need to look for ways to prevent that from happening,” and that in that case “We would have to come up with some form of required ID to meet that problem.” He and other Democrats said the debate should not assume the existence of widespread illegal voting as a reason to tighten identification standards.