What voter registration procedure is least likely to encourage participation?

The procedure requiring registration 30 days before election day is least likely to encourage participation because it creates a significant barrier for potential voters. This lengthy advance registration requirement can lead to disenfranchisement, as individuals may not be aware of the deadline or may not have the ability to register in advance due to various constraints, such as work obligations, mobility issues, or lack of access to registration resources. In contrast, same-day registration, online registration, and automatic registration methods are designed to make the process more accessible and user-friendly, thereby increasing voter participation. Same-day registration allows individuals to register on the same day they vote, which can capture those who may decide to participate spontaneously. Online registration provides a convenient option that can facilitate quicker and easier access, and automatic registration ensures that eligible citizens are registered as part of other bureaucratic processes, minimizing effort on their part.