The email containing an audio file that has rocked the Clinton campaign since last week when it was first reported by the Washington Free Beacon was one of thousands to and from a Clinton volunteer posted on a website believed to have ties to the Russian government.

Ian Mellul has worked for the White House since April 2015 according to his LinkedIn profile, but in February, as he volunteered for the Hillary Clinton presidential campaign, he sent an email to a top campaign press aide that would later provide fodder for Republicans and insight into Clinton’s private conversations with top donors.

The email, which Mellul sent to Nick Merrill, Clinton’s traveling press secretary, contained an audio file of Clinton’s remarks to donors at a McLean, Virginia, fundraiser. In her remarks, she derisively wrote off Sanders supporters and made other comments that would draw attention when the audio became public.

"Someone asked HRC a question about Sen. Senders towards the end, only thing I can think to flag!" Mellul wrote to Merrill on Feb. 16, 2016, the night of the fundraiser.

The Sanders question prompted a response from Clinton that has roiled the presidential race since Republican candidate Donald Trump seized on it on Saturday in an attempt to drive a wedge between Clinton and the energetic coalition that supported Sanders’ candidacy.

"Some are new to politics completely. They’re children of the Great Recession and they are living in their parents’ basement. They feel they got their education, and the jobs that are available to them are not at all what they envisioned for themselves, and they don’t see much of a future," Clinton said at the event.

Trump highlighted the comments in a Saturday speech. "Hillary Clinton thinks Bernie supporters are hopeless and ignorant basement dwellers," he said.

Clinton’s comments threaten to reopen divides from the Democratic presidential primary, which pitted Clinton’s hefty political machine against Sanders’ young and energetic base of support.

News of Clinton’s remarks came just days after the campaign held an event with Sanders promoting key issues of his presidential run, such as student loan forgiveness. The event was widely seen as an effort to court Sanders supporters who have lingering doubts about Clinton’s candidacy.

The email containing the audio file was one of more than 13,000 messages to and from Mellul’s personal Gmail account posted on the DCLeaks website.

Mellul, a White House advance staffer, has volunteered for the Clinton campaign since last year. Campaign finance records show the Clinton campaign has paid him more than $10,000 since then for expense reimbursements and "event consulting."

Cybersecurity specialists with the firm ThreatConnect said last month that they had traced DCLeaks’ web hosting and domain registration data to a group of Russian hackers called Fancy Bear, which is believed to have operated in collaboration with Russian intelligence services.