IOWA CITY, Iowa (AP) — County election boards began counting a record number of absentee ballots in Iowa on Monday, racing toward a Tuesday night deadline to have those votes tabulated.

Nearly 956,000 people had sent in their ballots by mail, dropped them off at auditor’s offices or voted early in person as of Monday morning. That is more than half of the likely total statewide turnout, which is expected to exceed 1.6 million.

In all 99 counties, bipartisan election boards could begin counting the absentee votes on Monday as allowed by state law. Some were planning to work all day and late into the evening before reconvening Tuesday.

Iowa law calls on counties to take steps to have absentee ballots counted by 10 p.m. on Election Night, an hour after polls will close Tuesday. But mailed ballots that are postmarked by Monday and arrive by noon on Nov. 9 will be counted as they arrive.

County officials say they are confident that, barring an equipment failure, power outage or some other unexpected problem, the boards will complete the counting by 10 p.m. on Tuesday as recommended by state law.

They noted that the largest counties have new high-speed machines that can process many thousands of ballots per hour, and counties were given extra time to begin processing ballots this year.

Under an emergency directive from Iowa Secretary of State Paul Pate, counties were given permission to meet Saturday to begin processing ballots before Monday’s count began.

“I believe and have faith we are going to do like we always have and deliver on time and look good,” said Scott County Auditor Roxanna Moritz, the chairwoman of the Iowa State Association of County Auditors.

Iowa is considered a competitive state in the presidential election between Donald Trump and Joe Biden, who are trying to win Iowa's six electoral votes. A Senate race between Republican incumbent Joni Ernst and Democrat Theresa Greenfield could also help decide partisan control of the U.S. Senate.

Democrats said Monday they are preparing for any potential Republican effort to stop the counting of absentee votes at 10 p.m. on Tuesday in the event that any counties fall behind.

Linn County Auditor Joel Miller, a Democrat, asked the secretary of state’s office last week to confirm in writing that counties had the authority to keep counting if they weren’t done by 10 p.m. Tuesday, as they have had to do on occasion in the past.

Miller noted that his county did not complete counting absentee ballots during the June primary until 4 p.m. on Election Day, and has far more to process this election. Miller said he was worried about what would happen if machines broke down in Linn County, the state’s second largest, where about 80,000 absentee votes must be counted.

The state’s director of elections, Heidi Burhans, did not answer his question about the 10 p.m. deadline. Instead, she responded that Linn County should have more than enough time to count all ballots by then.

Miller has been warning fellow county auditors that Pate, a Republican with whom he has often feuded, could try to suspend counting at 10 p.m. in an effort to boost Republicans. The county election board began counting at 7 a.m. Monday and planned to work through the night if necessary in hopes of getting done early, he said.

“We probably wouldn’t be working through the night if we didn’t have this threat,” Miller said.

Pate spokesman Kevin Hall said Monday that “every eligible ballot will be counted. Period.” Pate said at a news conference that he was “very comfortable” that counties will be finished by the time polls close.

Moritz, the chairwoman of the auditors association, said any county that hasn’t finished by 10 p.m. Tuesday would be handled on a case-by-case basis. She said she was confident that ultimately every vote would count.

The absentee vote is expected to heavily favor Democrats. More than 121,000 registered Democrats than Republicans have turned in absentee ballots, according to state data.

Republicans said Monday they were encouraged by new data showing they now have 20,000 more registered voters than Democrats statewide, an increase from the previous month. But voters who do not belong to either party are expected to outnumber them at polling places on Tuesday.