Preventing people who are not United States citizens from casting a ballot has reemerged as a focal point in the ongoing Republican drive to safeguard “election integrity,” even though noncitizens are rarely involved in voter fraud.

With polls showing unauthorized immigration as Republicans’ best issue for the fall, the GOP is looking to raise the alarm about voting by non-citizens and the undocumented, even though this kind of voter fraud is extraordinarily rare.

Congressional Democrats on Tuesday said they plan to again introduce a bill to set national voting standards in response to state legislatures passing strict voting laws.

Next year’s elections are still 16 months away. But for voters, perhaps the most important developments took place during the first half of this year — when states drafted and passed the legislation that will shape how those contests are run.