"I will do everything I can to stop the radical agenda coming from Nancy Pelosi's House," Graham said in his victory remarks Tuesday night. "So Speaker Pelosi, if you enact the agenda you're taking about, we're going to bury it in the Senate because it's bad for America."

"I've had two calls already, one from President Trump," Graham went on. "He's going to win. He is going to win. To all the pollsters out there: You have no idea what you're doing. And to all the liberals in California and New York, you wasted a lot of money."

"This is the worst return on investment in the history of American politics."

Graham won in part by portraying Harrison as a rubber stamp for the Democratic Party in Washington and by defending his close relationship with Trump, describing it as beneficial to his constituents.

Harrison rejected that argument, making the race competitive by focusing on local issues and largely eschewing Trump, who remains popular in the state.

"We proved that a new South is rising," Harrison said in his concession remarks Tuesday night. "Tonight only slowed us down."

"But a new South with leaders who reflect the community and serve the interests of everyone will be here soon enough," he went on. "Senator Graham and I may have our differences, but I hope he will maintain the spirit of cooperation he's known for while we take a step forward in creating a new South that is so possible."

In the final stretch of the campaign, Graham zeroed in on Justice Amy Coney Barrett’s confirmation to the Supreme Court, touting his role leading the effort as chairman of the Senate Judiciary Committee. He also warned of dire consequences if Democrats take control of the Senate, citing Democratic leaders’ vague threats of retribution if they win power.

Harrison sought to capitalize on Graham’s involvement in the confirmation process, hammering Graham over his reversal from 2018, when he said he would not move a Supreme Court nomination through the chamber in an election year. Barrett was confirmed just eight days before the 2020 election.

The Supreme Court fight accelerated an unprecedented flow of cash into the state, and especially into Harrison’s campaign. Harrison smashed Senate fundraising records, raising a staggering $57 million in the third quarter of 2020; Graham raised $28 million in the same time frame, less than half of Harrison’s haul but enough to set a record for a Republican Senate candidate.

A super PAC aligned with Senate Majority Leader Mitch McConnell (Ky.) spent tens of millions of dollars in the final days of the campaign, an indication that Republicans feared Graham could lose.

"All I can say is this has been overwhelming," Graham said Tuesday night. "I've never been challenged like this. And I've never had more support than I do tonight. There are people all over this country [who] came to my aid. There are people who had never given 15 cents, gave me what they could."

"Ted Cruz's mother sent me 30 bucks."

Harrison sought to portray Graham as a hypocrite who long lost touch with South Carolinians as he cultivated relationships in Washington. Harrison largely avoided criticizing the president throughout the campaign, knowing it would be a risky gambit in a state where Trump remains popular.

At 65 years old, Graham has served in Congress for 25 years. His tenure began with four terms in the House of Representatives, where he gained national prominence as an impeachment manager in the trial against President Bill Clinton.

While he ran as a conventional Republican in 2020, Graham has long drawn the ire of conservatives. During his 2014 reelection campaign, Graham took the so-called tea party head-on, highlighting his bipartisan credentials and moderate views on immigration, gun control and other issues.

Harrison, 44, worked on Capitol Hill and as a lobbyist before returning home to South Carolina. He served as the chairman of the state’s Democratic Party for four years and currently serves as an associate chairman of the Democratic National Committee, after losing a run for the chairman’s job in 2017.

Eleanor Mueller contributed to this report.