LOUISVILLE, Ky. — With only one polling place designated for Louisville on Tuesday, voters who didn't cast mail-in ballots or show up early could face long lines in Kentucky's primary election, the latest to unfold in a pandemic that's triggered unprecedented election disruptions across the country.

The outcome of a competitive Democratic U.S. Senate primary could hang in the balance if Election Day turnout is hampered in Louisville — the hometown of Charles Booker, who's mounted a strong late challenge against presumed front-runner Amy McGrath.

"If Charles Booker barely loses, I think the integrity of that election is in question," Republican state Rep. Jason Nemes said Monday.

The primary's winner will go against Senate Republican leader Mitch McConnell, who isn't expected to see a serious GOP primary challenge, in November.

The state's Republican secretary of state, Michael Adams, said he's "cautiously optimistic" long lines won't force people in Louisville to wait hours before voting. Early voting opened statewide two weeks ago. That, along with strong demand for absentee ballots, could spare people in Louisville or elsewhere from long waits, Adams said Monday.

Nemes sued to get more in-person voting locations in the state's most populous counties. A federal judge denied the request days before the election.

The surge of absentee ballots could cause waits of another sort Tuesday, as some counties have said they won't release vote totals before June 30.

Kentucky turned to widespread mail-in absentee voting in an agreement between the Democratic governor and Adams in response to the coronavirus outbreak. But many voters not requesting absentee ballots will head to the polls Tuesday. Each county submitted a plan to the state on how many polling places to open. The state's primary is typically in late May but was delayed.

Many states pushed their elections back to manage an onslaught of poll worker cancellations and consolidation of polling places. They also sought time to push more voters to cast absentee ballots.

New York also has a primary Tuesday and has consolidated some polling sites. Erie County — home to the state's second-largest city, Buffalo — will see 40% fewer polling sites.

State board of elections spokesman John Conklin said he hopes the consolidation plan will have "minimal" impact on voter turnout and access.

State election workers were trying to get 1.8 million absentee ballots to New Yorkers. County boards of elections have scrambled to process 11 times as many ballot applications as they did for the 2016 primaries without extra state funding, Conklin said.

In Louisville, a city of 600,000, the only in-person Election Day voting place is at the state fairgrounds. Despite waves of mail-in voting, some braced for long lines and frustration.

"There will be a number of people who want to vote tomorrow but will be discouraged from voting because it's much too difficult," Nemes said.

That's of particular concern for Booker, who's Black and counting on a high turnout in Louisville. He said his campaign would "keep a watchful eye" and stands ready to mount a legal challenge if needed.

"There should not have only been one location," Booker said. "That will just naturally disenfranchise folks."

McGrath tried to join the suit demanding more than one in-person voting location on Election Day in Louisville and other population centers, but a federal judge denied her campaign's motion to intervene. McGrath also pushed to extend the deadline for requesting an absentee ballot.

For voters unable to get absentee ballots, "you are forced to now stand in line in the one polling location in the middle of a pandemic," McGrath said. "If you're 82 years old, are you going to do that?"

In Lexington, the state's second-largest city, the voting location is at the University of Kentucky's football stadium. 

Louisville Metro Council member Barbara Sexton Smith said she's worried about the prospect of long lines at the fairgrounds.

"In a 21st-century America, it's a shame that we are making people go to such great, dangerous lengths, with the COVID pandemic, just to exercise their right to vote," she said.

Richard Beliles, Common Cause Kentucky board chairman, said offering "so few polling places for the primary is irresponsible and unacceptable, and sadly it was avoidable."

Georgia delayed its primary twice to give election officials more time to prepare, sending absentee ballot applications to every active registered voter in the state. That wasn't enough. When Georgia held its primary June 9, metro Atlanta voters waited up to 10 hours. As in Milwaukee and Philadelphia, many of the lines were concentrated in minority communities, sparking objections from voting rights advocates.

Even in Nevada, where absentee ballots were sent to every registered voter for the June 9 primary, large-scale consolidation caused problems. The last voter in Las Vegas to cast a ballot did so at 3 a.m., eight hours after polls were supposed to close.

In Kentucky, Adams said: "There are going to be lines — 30, 45 minutes, maybe an hour, maybe longer." He added: "We don't think anyone will be disenfranchised."

At the fairgrounds in Louisville, after being directed into the large hall, voters will wait in line spaces about 6 feet (1.83 meters) apart by chalk markings on the floor, before heading to cast their votes. Hand sanitizing stations are available when exiting the voting area.

Jefferson County, which includes Louisville, sent out 218,404 absentee ballots to voters who requested them by the June 15 deadline, according to the county clerk's office. As a comparison, about 125,000 people voted in the 2016 U.S. Senate primary in Jefferson County.

The county also allowed early in-person voting beginning June 15 at the state fairgrounds. Last week nearly 7,500 people walked in and voted early between Monday and Friday, county clerk spokesman Nore Ghibaudy said. Voters have also been allowed to vote early in-person at the county's election center near downtown since June 8.

More than 883,000 absentee ballots were requested statewide, with slightly more than half filled out and sent in, Gov. Andy Beshear said. More than 88,000 Kentuckians voted in-person early, he said.