An aide to Tom SteyerThomas (Tom) Fahr SteyerSteyer aide stole Harris volunteer data in South Carolina: report Poll: Biden leads Warren by 8 points in Nevada Second-tier Democrats face do-or-die phase MORE’s presidential campaign in South Carolina resigned on Monday following an internal investigation after it was discovered he had downloaded volunteer data from Sen. Kamala HarrisKamala Devi HarrisCastro campaign laying off staffs in two states: report Steyer aide stole Harris volunteer data in South Carolina: report Harris becomes fifth candidate to qualify for December presidential debate MORE’s (D-Calif.) 2020 campaign.

Dwane Sims, who served as Steyer’s deputy state director in South Carolina, was placed on paid administrative leave over the weekend. It's unclear if he was pressured to resign or did so on his own.

“The Steyer campaign takes this issue very seriously,” campaign manager Heather Hargreaves said in a statement. “When we first learned about the matter, we conducted an internal investigation and wiped Mr. Sims’ computer to make sure the data was completely deleted and that there was no access to other campaign data. We understand the sensitivity and importance of this information.”

The Steyer campaign and the South Carolina Democratic Party differ on how Sims was able to gain access to the data.

Hargreaves said it occurred after the state Democratic Party restored the Steyer campaign’s access to its voter files following a brief lapse. 

The file access had been temporarily revoked because of a miscommunication between the campaign and the party over payment, according to a Steyer aide.

Sims, himself a former South Carolina Democratic Party employee, notified party officials minutes after learning that he was able to see rival campaigns’ data, and the access was revoked, Hargreaves said.

“We apologize to the South Carolina Democratic Party and the [Democratic National Committee],” she continued. “Tom Steyer and the Steyer campaign extend our deepest apology to Senator Kamala Harris and her campaign.”

That Sims had accessed Harris campaign data was first reported on Monday by the Post and Courier newspaper in Charleston, S.C. 

According to the South Carolina Democratic Party, however, Sims gained access using an account he had retained from his time as a voter file manager there. 

Sims left the party at the end of September to join Steyer’s campaign. At the time, the party disabled access to his accounts, according to a state party official. 

But the party learned that Sims had retained access to a separate, unknown user account, the official said, a violation of Democratic National Committee (DNC) rules.

The DNC found out on Friday that Sims had access to the data and called him at 2:56 p.m. to discuss the matter, a DNC official familiar with the matter said. In that conversation, which lasted about 12 minutes, the official said, Sims described the data and was told that his account would be immediately disabled to prevent him from accessing the information.

Once Sims’s account had been disabled, the DNC reviewed the activity log to make sure that no data had been accessed inappropriately and discovered that Sims had downloaded Harris campaign data at 3 p.m., while he was on the phone with the DNC, the committee official said.

The DNC said it sent him a cease-and-desist letter. It later received confirmation from Sims that he had deleted the stolen information, which included thousands of volunteer contacts.

Trav Robertson, the chair of the South Carolina Democratic Party, said that Sims did not have access to the data of any other campaign and confirmed that the downloaded data had since been destroyed.

“All data downloaded by this individual was destroyed and was not provided to any third parties,” Robertson said in a statement. “It is critical that the Steyer campaign take immediate action regarding their employee. This user account did not have access to data from any other presidential campaign.”

Sims has been banned from accessing the Democratic Party’s voter database and systems.

Harris has placed a particular emphasis on her efforts in South Carolina, the fourth state to vote in the 2020 Democratic nominating contest and the first in which a majority of the Democratic electorate is African American.

A spokesperson for Harris’s campaign did not immediately respond to The Hill’s request for comment on Sims’s resignation. But Ian Sams, the campaign’s national press secretary, tweeted on Monday that the attempt to access Harris’s volunteer data was “unfortunate.”

“Our organizers and volunteers work incredibly hard, and as this story notes, our campaign ‘has built a particularly extensive field organizing operation in South Carolina,’ ” Sams tweeted, referring to the Post and Courier’s reporting on the matter. “It's unfortunate anyone would try to steal that work from our team.”