SIOUX FALLS, S.D. (AP) — More than 100 absentee ballots in one of South Dakota's least conservative counties should not have been rejected after being challenged by the leader of a group that has raised doubts about the state's voting system, an elections official said.

Jessica Pollema, president of the conservative group SD Canvassing, challenged absentee ballots in two Minnehaha County precincts that were cast in the state's June 4 primary election. She alleged that voter registration forms were either incomplete or listed addresses that weren't where voters actually lived, in violation of state and federal law, according to her letter to the county.

One precinct board denied her challenge, but the other rejected 132 of 164 challenged ballots, County Auditor Leah Anderson confirmed. South Dakota is one of the country's most conservative states, but that precinct is in a legislative district represented by all Democrats. In the 2020 presidential election, Minnehaha County, which includes the state's largest city, Sioux Falls, voted for Donald Trump by a much smaller margin than the state as a whole.

Pollema declined to comment to The Associated Press. Her group supports petition efforts to prohibit ballot tabulating machines and move to hand counting, among other goals, such as banning mail-in voting. The group's challenges come amid broader Republican challenges to voter rolls in presidential battleground states — of which South Dakota isn't one.

The South Dakota Secretary of State's Office was made aware of the challenge and rejected ballots, and had advised a Minnehaha County official as to what state law deemed as challengeable, though “what was being challenged didn't fall into those parameters,” said Rachel Soulek, director of the office's elections division.

“This is a county level matter that we are closely watching, but we are deeply concerned and care about the voting right of all eligible voters,” she said.

Anderson said the precinct board made an effort to contact the voters who were challenged, but only had until 7 p.m. on Election Day to reach them.

“After that time, they are no longer officially the precinct board, so they did the best they could to reach out to the voters,” Anderson said.

Minnehaha County State's Attorney Daniel Haggar didn't immediately respond to a Monday request for comment.

About 13,000 ballots were cast in Minnehaha County in the June 4 election, which is about 10% of registered voters there, according to the secretary's website.