A federal judge ruled Thursday that 133 rejected ballots in the contested 2nd Congressional District race will not be counted.
The ruling is a blow to incumbent Democrat Ron Barber, who trails Republican Martha McSally by 161 votes.
The Barber campaign had asked the judge to delay the official statewide election canvass scheduled for Monday, until the 133 ballots were counted.
The ballots had initially been disqualified for a number of reasons, such as voters casting ballots in the wrong precinct.
But lawyers for the Barber campaign argued those voters had received misinformation from poll workers.
The judge rejected the request to count the ballots, arguing it was not clear they would undermine the integrity of the race, and the hardship of postponing the canvass would be greater to the Secretary of State and the public than the hardships faced by the Barber campaign.
The tight margin of the race means there will be an automatic recount, though it will not include those 133 ballots.
Meanwhile, McSally has already declared victory and went through Congressional freshman orientation in Washington.
The Associated Press contributed to this report.