COLUMBIA, S.C. (AP) — U.S. Sen. Lindsey Graham faced three little-known GOP challengers on Tuesday, his last step before an expected general election face-off with Democrat Jaime Harrison in what's on pace to become the most expensive race in South Carolina history.

With Graham expected to easily win among Republicans and Harrison running unopposed on the Democratic side, Tuesday's primaries lacked the kind of top-of-the-ballot choice that could drive turnout by voters leery of exposing themselves to the coronavirus pandemic.

And many voters mailed in their choices instead; as of Tuesday morning, 83,607 absentee ballots were returned for the Democrats and 80,380 for the Republicans, according to the South Carolina Election Commission.

A slow but steady trickle of voters cast ballots in person Tuesday at a church in Lexington, South Carolina, where supporters of some local candidates said there was no line inside. Those wearing masks often took them off as soon as they left.

Ed Spratt, 63, of Lexington, arrived at the church and left his mask in his car, though he acknowledged he should have worn it inside. Spratt said of voting in-person during the pandemic: “It wasn’t a concern in the forefront. It’s always there, but it was not, ‘Oh god, I can’t go vote today.”

Tom Chandler, dean of the Arnold School of Public Health at the University of South Carolina, arrived at midday at his polling place at a church near Lake Murray. He wore a black face mask.

Though strips of blue tape outside guided voters to stand six feet apart, no line formed.

“As a public health professional, yes, I’m concerned about it,” Chandler said of voting in person during the pandemic. “But you know, my desire to exercise my right to vote far outweighs my concern for my personal safety from COVID.”

Chandler said his polling place did an excellent job with safety precautions, including providing voters with cotton swabs to use on the ballot machine screens.

Graham, 64, faces fellow Republicans Duke Buckner, Michael Lapierre and Joe Reynolds. Buckner, an attorney and former Walterboro city councilman, and Lapierre, a retired corporate executive from Pickens, have argued Graham isn’t conservative enough.

Reynolds, a Merchant Marine engineer from Charleston, has said new leadership is needed in Washington. Graham is seeking his fourth term.

Graham's popularity among Republicans in his home state has recently fluctuated along with his relationship to President Donald Trump, who is supporting his reelection bid and campaigned with him in the state in February. A year ago, all of South Carolina's statewide-elected officials endorsed Graham, as has Vice President Mike Pence, who helped kick off Graham's campaign last year.

The 44-year-old Harrison, an associate chairman with the Democratic National Committee and former chairman of the South Carolina Democratic Party, has aimed to draw national attention from the start, helping him attract the fundraising and grassroots organizing crucial to flipping a Senate seat in a deeply red state.

With support from former Vice President Joe Biden, Sens. Kamala Harris and Cory Booker and the Democratic Senatorial Campaign Committee, he's raised nearly $15 million to Graham's $21 million, according to Federal Election Commission records.

Two Libertarians and one Constitution Party candidate also filed to seek the seat.

The pandemic raised some challenges for Tuesday's voting. During one of their brief returns to the Statehouse, legislators passed a law allowing universal absentee voting, and a federal judge also temporarily removed a requirement that a witness sign each absentee voter's ballot.

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Associated Press writer Michelle Liu in Lexington, South Carolina, contributed.

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Meg Kinnard can be reached at http://twitter.com/MegKinnardAP