Emails made public Sunday by WikiLeaks suggest Hillary Clinton's campaign manager had a "close" relationship with Bob Creamer, the Democratic operative who recently resigned in the wake of footage that suggested he had accepted money from the Democratic National Committee in exchange for inciting violence at Donald Trump's rallies.

In a Dec. 2015 email to Neera Tanden, co-chair of Clinton's transition team, a progressive activist named Michael Lux encouraged Tanden to consider involving Creamer further in the campaign's efforts to court Bernie Sanders' supporters.

"Just wanted to pass along this note I sent to Bob Creamer, who as you may know is consulting for the DNC and is close to Robby Mook," Lux wrote to Tanden.

Mook is Clinton's campaign manager. Lux went on to describe his frustration with Clinton's failure to cultivate relationships within the progressive movement.

Tanden forwarded the note on to John Podesta, Clinton's campaign chair, and specified the message had come from his "buddy."

Creamer, who had worked for a progressive advocacy group called Democracy Partners, and Scott Foval, another Democratic operative, were caught in an undercover video sting orchestrated by conservative activist James O'Keefe describing efforts to start physical altercations outside Trump's rallies during the primary race.

Donna Brazile, acting chair of the DNC, dismissed Creamer as a "temporary regional sub-contractor" who had spoken of events that never actually occurred.

What's more, Mook denied last week that he had ever known Creamer and Foval. Asked about the two operatives during an Oct. 23 interview on CNN's "State of the Union," Mook said "they've never had a relationship with the Clinton campaign."

But the lastest email from WikiLeaks suggests Creamer had deep ties to the highest levels of Clinton's campaign.

WikiLeaks has released nearly 37,000 emails from Podesta's inbox to date. The transparency website claims to have up to 50,000 emails in its possession.