OREGON CITY, Ore. (AP) — Problems with a ballot-sorting machine are slowing the vote tally in a suburban Portland county that was also plagued by counting issues in 2022 and is home to a key congressional race this year.

The sorter in Oregons third-largest county, Clackamas, began experiencing mechanical issues about a week after ballots were mailed to voters in mid-October, elections officials said Thursday.

At times it abruptly stops moving ballots, making it difficult to process a large volume without interruption. The issue also has delayed voters’ ability to track whether their ballots have been counted, officials said.

Representatives from the company that manufactured the sorter have been on site trying to fix it.

County Clerk Catherine McMullen, who was elected in 2022, told The Oregonian/OregonLive on Wednesday that ballot processing was “about a day behind where we want to be.”

Clackamas County makes up a large part of U.S. House District 5, considered to be one of the nations closest races as a Republican incumbent seeks to hold a seat she narrowly flipped from Democrats in 2022.

That same year a printing error on primary ballots delayed results for nearly two weeks as tens of thousands of ballots with blurry barcodes were rejected by a counting machine, forcing the county to shift nearly 200 employees to vote tabulation duties.

This year U.S. Rep. Lori Chavez-DeRemer faces a tough reelection bid in the district, where voters preferred President Joe Biden over Trump by almost 10 percentage points in 2020. The Democratic nominee is state Rep. Janelle Bynum.

Elections workers are now processing incoming ballots using hand scanners, a practice currently used in smaller Oregon counties and last used in Clackamas County in 2015, officials said. Workers continue taking in mailed ballots as well as those placed in drop boxes at the same rate and are processing ballots in the order they are received.

As of Wednesday night, officials said nearly 83,000 ballots had been processed.