The sudden death of four-term Sen. Lindsey Graham this weekend has injected even more uncertainty into a turbulent midterm campaign season.

At the time of his death, the South Carolina Republican was running for his fifth six-year term. Last month, he handily defeated his primary challengers, a field that included conservative insurgent Mark Lynch.

He was set to face the Democratic nominee, pediatrician Annie Andrews, in November. On Sunday, Andrews issued a statement offering her condolences to Graham’s family and asking South Carolina residents to join her in “setting partisanship aside and offering gratitude” for Graham’s decades of service to the state.

Graham’s death will likely set off a struggle for the seat among Republicans in the reliably red state. Under South Carolina law, the Republican vacancy will be filled in a special primary election to be held by Aug. 11, with a runoff election between the top two finishers scheduled for Aug. 25 if none of the contenders receive a majority of the vote.

“Lindsey Graham is irreplaceable. What you do, however, is you try to move on, and our state will have to move on,” Sen. Tim Scott, R-S.C., said Sunday on ABC’s “This Week” program. “I think August will be a very busy month in South Carolina as we start the process of finding the Republican nominee for this November’s ballot.”

Potential candidates for the full term include Rep. Nancy Mace, who lost the GOP gubernatorial primary and Lt. Gov. Pamela Evette, who lost the GOP primary runoff for governor. Lynch, who lost the primary to Graham, 57 to 29 percent, is another possible candidate.

For her part, Mace, who lost the gubernatorial primary last month, didn’t disavow rumors of her interest, tweeting a gif on Sunday morning with the famous “Godfather Part III” quote from Michael Corleone —”Just when I thought I was out … they pull me back in.”

In the meantime, Republican Gov. Henry McMaster is empowered to appoint a senator to fill the remainder of Graham’s term, which ends in January.

One possible contender for the caretaker Senate seat took himself out of consideration Sunday: Rep. Joe Wilson, whose son, state Attorney General Alan Wilson defeated Evette to become the GOP nominee for governor, cited Republicans’ slender hold on the House majority as the reason.

“I was grateful to speak with President Trump today reminiscing about our mutual friend, Senator Lindsey Graham,’’ Rep. Wilson posted on social media. “I assured him my goal is to remain in the House to keep his two-vote majority for the American people!!!”

President Donald Trump, speaking on NBC’s “Meet the Press,” where Graham was scheduled to appear Sunday, said he has someone he favors to replace Graham but declined to say who.

“I have somebody that I think would be great, but I don’t want to say it now because … it’s too soon with Lindsey,” Trump said. “I don’t want to even talk about anybody, but I do have somebody that I think is really good.”

The president said he spoke to Graham, who was fresh off a visit to Ukraine, early Saturday evening and he sounded “a little tired.”

Trump said he was informed of Graham’s passing around 1 a.m. Sunday by a member of the late lawmaker’s Senate staff.

Mary Ellen McIntire, John T. Bennett and David Lerman contributed to this report.