A Texas judge has blocked an order allowing only one absentee vote drop-off point per county, claiming it would affect older and disabled voters.
Drop-off points were set up to allow voters to submit ballots in advance rather than rely on the postal service.
Texas Governor Greg Abbott, a Republican, said the number of drop-off points needed to be minimised to guarantee voter security.
Democrats said the move was blatant voter suppression.
A record number of people are expected to vote by mail in this year's election due to the pandemic.
The US Postal Service already has already warned ballot papers may not arrive in time to be counted on election day, 3 November.