NYT analysis by Eric Eckholm:

Numerous reports of voters facing obstacles have emerged from early voting in Texas and Georgia, among other states. But quantifying the impact of the altered rules is challenging, especially in a midterm election expected to have low turnout. In states like North Carolina, liberal groups hope that public anger over curbed voting opportunities will provoke a backlash that motivates Democratic voters, offsetting possible losses.

The battles over election rules have partisan roots, said Richard L. Hasen, a law professor at the University of California, Irvine, and the editor of Election Law Blog.

“One lesson learned from Florida in 2000,” he said, referring to the counting fiasco in the contest between George W. Bush and Al Gore, “is that in close elections, the rules matter a great deal.”

Both parties, Mr. Hasen said, assume that restrictions like photo ID requirements and the elimination of same-day registration most often deter less-engaged voters who are more likely to vote Democratic. “So unsurprisingly, Democrat-led legislatures have passed rules making it easier to register and vote, and Republicans have done the opposite,” he said.