The sweeping shift to mail-in voting that took place in 2020 has been reversed in some critical swing states, a potential blow to Democrats eager for a repeat of the pandemic free-for-all that many argue led to Joe Biden's victory. 

States like Wisconsin, Pennsylvania and Georgia have new restrictions on mail-in voting, but other states have made a permanent shift to the more relaxed rules ushered in during COVID.

Shift in voting landscape

In Nevada, rules adopted in 2020 are now permanent: once again, mail ballots will automatically be sent to voters, ballots can be returned by third parties, and there will be drop boxes in every county.

Democrat-run Michigan is similarly making drop boxes widely available, along with nine days of early voting and pre-paid postage for mail ballots. Voters who cannot prove their identity will be allowed to sign a sworn affidavit instead.

Pennsylvania adopted automatic voter registration last year, but voting by mail is a little stricter than in 2020, when ballots postmarked by Election Day were acceptable up to three days late.

Mail ballots must now be returned by Election Day to be counted, and a court recently ruled that mail-in ballots must have correct, legible dates.

North Carolina, a Republican-leaning swing state, will require all voters to show ID for the first time after a lengthy court battle, and a copy of a photo ID must be included in return envelopes with mail ballots.

2020 casts a shadow

Wisconsin governor Tony Evers, a Democrat, has asked the state's Supreme Court, which was taken over by liberals last year, to reverse a ban on ballot drop boxes.

“Drop box voting is safe and secure, and there is nothing in Wisconsin’s election laws that prohibit our local clerks from using this secure option," he said.

Disputes over voting have been shaped by ongoing disagreements over the 2020 election, which was decided after a lengthy delay caused by mail-in voting on an unprecedented scale.

Republicans have prioritized returning to in-person voting with ID, while Democrats have doubled down on more relaxed, pandemic-era measures.

While voting rules continue to be disputed, the results in swing states could also be impacted by state court rulings on topics like abortion.

Democrats are seeking to make the election a referendum on abortion, an effort that was helped Tuesday by a state Supreme Court ruling in Arizona that revived an 1864 abortion ban.