Jaime Harrison

Former South Carolina Democratic Party chairman Jaime Harrison spoke at the Democratic National Convention in 2016. Harrison filed paperwork Thursday to form an exploratory committee for a campaign against U.S. Sen. Lindsey Graham, R-S.C. AP Photo/J. Scott Applewhite

WASHINGTON — Democratic operative Jaime Harrison filed federal paperwork Thursday forming an exploratory committee to likely challenge South Carolina's Republican senior senator, Lindsey Graham.

The former S.C. Democratic Party chairman, who is now an associate chairman and counselor at the Democratic National Committee, has stoked speculation for months he would run against Graham, who is up for re-election in 2020.

The statement of organization for his exploratory committee, submitted to the Federal Election Commission on Thursday, is the first official step.

Harrison confirmed to The Post and Courier he is planning to publicly lay out his plans in more detail Friday. His campaign website, jaimeharrison.com, has already gone live.

In a recent interview, Harrison said he has been thinking extensively about how to beat Graham and start a "new chapter" in a state where no Democrat has won a statewide race since 2006.

"What it's going to take is someone who has a vision for what South Carolina can be and who is focused solely on South Carolina," Harrison said. "The one big thing with Lindsey is his focus has been on a lot of other things."

Harrison said Thursday he is under no illusions about how difficult the race will be.

"South Carolina is a hard nut to crack for a Democrat, and nobody knows that better than me," Harrison said. "But my passion has been how we make this state and all of the South competitive again for both parties."

Harrison was scheduled to appear Thursday night at a North Charleston live taping of the podcast Pod Save America, which is hosted by several Obama administration alums. The episode, in which Harrison is expected to discuss is forthcoming Senate campaign, will be released Friday.

Graham, who was first elected to the Senate in 2002, recently took over as chairman of the Judiciary Committee. Asked earlier this week whether he is concerned about Harrison's potential run, Graham said he expects to win but will not take anything for granted.

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“I run like I’m behind," Graham said. "I’m not owed this job, I have to earn it. I think I’ve got a good story to tell about my time as senator. I think, when it comes to me, the best is yet to come.”

While Senate races in several other states that have historically been more competitive are expected to draw more national attention, Graham's friendly relationship with President Donald Trump has made him a top early target for the South Carolina Democratic Party and progressive grassroots activists.

An Orangeburg native, Yale graduate and top Democratic Party official, Harrison has cultivated a vast political network that could help give him the resources to launch a well-funded run against Graham.

He was also once an aide for U.S. Rep. Jim Clyburn of Columbia, the state's most influential Democrat, and a lobbyist for the Podesta Group, which was co-founded by Bill Clinton presidential campaign chairman John Podesta.

Graham starts the race with more than $3.2 million, according to his most recent federal disclosures, giving the incumbent Republican the biggest campaign war chest of any politician in the state. Scott Farmer, who led Graham's last two successful reelection bids, is returning as his campaign manager.

Follow Jamie Lovegrove on Twitter @jslovegrove.

Jamie Lovegrove is a political reporter covering the South Carolina Statehouse, congressional delegation and campaigns. He previously covered Texas politics in Washington for The Dallas Morning News and in Austin for the Texas Tribune.