The Lancaster County Board of Elections on Tuesday reported issues with its mail-in ballots, stating that a mistake by a vendor left it unable to scan thousands of ballots because it printed them with the wrong identification codes.

County officials called the error "unacceptable."

"About 22,000 mail ballots were printed by the print vendor with the incorrect code and could not be read by the county’s scanners," the secretary of state's office told ABC News. "County election officials will re-mark the ballots by hand and then scan them. This is allowed under [Pennsylvania] law. It is likely to take county officials a few days."

It’s unclear how the glitch will impact the election. Polls close at 8 p.m. ET in the state, where voters are choosing their party’s nominees for Senate and governor.

The first poll closure of the night comes in Kentucky, where Republican Sen. Rand Paul is seeking a third term and ABC News projected he will win the GOP primary.

Paul has garnered national recognition for his libertarian-leaning views and recently made headlines for single-handedly delaying a $40 billion aid package for Ukraine, which ultimately passed with bipartisan support. Five other Republicans had challenged Paul in the primary race, though he was expected to easily clinch the nomination and win the general election in November.

On the Democratic side, ABC News projected Sen. Charles Booker would win the Senate primary.

Booker rose to prominence in the 2020 election cycle when he nearly upset a well-funded, establishment-backed Democratic rival in a Senate primary to challenge Republican leader Mitch McConnell.

Pennsylvania Lt. Gov. John Fetterman, the front-runner in the state's Democratic Senate primary race, has completed a "successful procedure" to recieve a pacemaker and defibrillator, his campaign said Tuesday, after he suffered a stroke late last week.

"John Fetterman just completed a successful procedure to implant a pacemaker with a defibrillator. The procedure began at 3:15pm, John was released at 5:56pm, and he has been given the all-clear that it was successful. He is resting at the hospital and recovering well. John continues to improve every day, and he is still on track for a full recovery," the campaign said in a statement.

Dr. Jay Bhatt, an internal medicine physician, instructor at the University of Illinois School of Public Health and ABC News Contributor, said the procedure to implant a defibrillator and pacemaker are "common but carry risks of infection, bleeding, and complications and inappropriate shocks from the defibrillator."

A day after Fetterman announced his stroke, his team said that he would not be attending his election night party and would remain in the hospital. His wife, Gisele, will speak in his place. His campaign released a photo Tuesday morning of Fetterman voting with an emergency absentee ballot from the hospital, where he is recovering.

Republicans are looking to keep the seat held by Sen. Pat Toomey, R-Penn., who said he would retire, which would be a critical gain for Democrats in their effort to maintain their slim control in the Senate.

Former President Donald Trump announced his endorsement of Dr. Mehmet Oz in April, asserting that Oz would be the one most likely able to win the general election for Republicans. But within the past couple of weeks, conservative commentator Kathy Barnette has seen a surge in support. As reported by ABC News’ Lalee Ibssa, voters at Trump’s rally in Pennsylvania, an event meant to bolster Trump’s pick, were skeptical of Oz.

But Barnette’s recent prominence has brought to light a series of Islamophobic and inflammatory comments she has posted to social media, as well as images first shared by an independent researcher of Barnette marching toward the Capitol. ABC News has verified two videos, one showing Barnette walking behind a man indicted in connection with the day’s events who prosecutors described as “a self-identified member of the Proud Boys.

Barnette’s campaign told NBC, "Kathy was in DC to support President Trump and demand election accountability. Any assertion that she participated in or supported the destruction of property is intentionally false. She has no connection whatsoever to the proud boys."

Following her surge in the polls, Trump said of Barnette: "She has many things in her past which have not been properly explained or vetted, but if she is able to do so, she will have a wonderful future in the Republican Party -- and I will be behind her all the way."