The United States on Tuesday called on Venezuela to reverse a ban on opposition members from holding office and participating in the Dec. 6 parliamentary elections.
Washington made the request after opposition leader Maria Machado said she had tried to register on Monday as a candidate but her application was rejected.
The State Department said in a statement that the decisions by Venezuelan electoral officials "clearly have the intention of complicating the ability of the opposition" to contest the poll and to limit the field of candidates.
"We call on all relevant Venezuelan authorities to reconsider the ban imposed on candidates, and reiterate our call for credible and timely electoral observation," the State Department said.
The State Department's criticism comes as the United States and Venezuela have opened a cautious rapprochement in the past few months to try to improve relations after more than a decade of acrimony.
Part of the discussion has been about ensuring a free and fair vote. Polls suggest the ruling Socialist Party could lose.
Washington has pressed Caracas to release political prisoners and allow outside observers to monitor the election.