Pennsylvania’s nationally watched U.S. Senate race is likely headed to a recount as incumbent Sen. Bob Casey did not waive an automatic recount.

The Associated Press called the race last week for Republican Dave McCormick who narrowly leads three-term Democrat Casey by less than 0.5%, the threshold for triggering an automatic recount under state law unless new returns pull it back over half a percent.

As the trailing candidate Casey had until noon Wednesday to waive his right to a recount and he did not do so, the Pennsylvania Department of State confirmed in a statement. Casey still trails McCormick by nearly 30,000 votes.

Secretary of State Al Schmidt is still waiting for unofficial returns from Pennsylvania’s 67 counties, the department said, and will determine based on those returns whether an automatic recount is warranted.

Schmidt must call for a recount by 5 p.m. Thursday and must alert candidates to the possibility 24 hours in advance, or 5 p.m. Wednesday.

If a recount is called counties are required to start the process by Wednesday, Nov. 20, at the latest. They must complete their recounts by Tuesday, Nov. 26.

Recounts often result in the final tallies of votes changing slightly for each candidate. But those corrections can go in either direction and usually only impact an extremely small fraction of votes. It is exceedingly rare for a recount to change the ultimate outcome of a statewide race, especially one divided by around 30,000 votes.

While Casey held a lead in polls for much of the campaign, the race tightened in the final days, and McCormick was leading as voters were counted in the days after the election. But his advantage shrank and fluctuated over time as some larger counties processed their provisional ballots, as of Wednesday it was within the 0.5% threshold.

Remarkably, this will be the second recount McCormick is involved in – in just his second competitive election. During Pennsylvania’s 2022 Senate race, McCormick fell short to Mehmet Oz in the GOP primary by fewer than 1,000 votes following a recount.

McCormick has projected confidence that his lead will hold, even as he has pursued challenges to the counting of some ballots.

After Senate Majority Leader Chuck Schumer (D., N.Y.) initially withheld an invitation, McCormick is attending orientation for incoming senators this week.

“I don’t care who voted for me and didn’t vote for me,” McCormick said Friday in a victory speech. “Today, I turn the page. I am focused on serving every single Pennsylvanian.”

But Casey’s campaign has been holding out hope, releasing daily statements reaffirming that votes are still being counted in Pennsylvania.

“My priority has always been standing up for the people of Pennsylvania. Across our Commonwealth, close to 7 million people cast their votes in a free and fair election,” Casey said Tuesday morning. “Our county election officials will finish counting those votes, just like they do in every election. The American democratic process was born in Pennsylvania and that process will play out.”

In a statement, Wednesday morning, Casey’s campaign manager Tiernan Donohue criticized McCormick for continuing to pursue litigation that would segregate or throw out ballots.

“David McCormick and his allies are trying to disenfranchise Pennsylvania voters with litigation designed to throw out large tranches of votes that they’ve admitted in legal filings could impact the outcome of the election.,” Casey campaign manager Tiernan Donohue said in a statement.

This is a developing story.