Donna Brazile, acting chair of the Democratic National Committee, vowed to serve as Hillary Clinton's "biggest surrogate" in January, a full month before voters cast the first ballots of the Democratic primary.

Brazile's statement of support came in an email to John Podesta, Clinton's campaign chair, that was published Wednesday by Wikileaks. The website has released nearly 7,200 Podesta emails in five batches, all posted online since late last week.

"As soon as the nomination is wrapped up, I will be your biggest surrogate," Brazile wrote in a Jan. 3 note to Podesta. At the time, she was vice chair of the DNC, and Clinton was locked in a surprisingly competitive primary battle with Sen. Bernie Sanders.

"Wishing you a happy New Year. 2015 was challenging, but we ended in a good place thanks to your help and support," Podesta had written to Brazile. "Look forward to working with you to elect the first woman President of the United States."

Brazile's predecessor, Rep. Debbie Wasserman Schultz, was forced to resign in July after Wikileaks published internal DNC emails that suggested she had worked quietly to ensure Clinton became the party's nominee instead of Sanders.

However, the emails stolen from Podesta's inbox have provided fresh evidence that Brazile also aided Clinton during the primary.

For example, one email from March showed Brazile gave the Clinton campaign a particularly tricky question in advance of a CNN townhall so Clinton's staff would have time to prepare an answer.

Brazile denied displaying any preference for Clinton during the primary, arguing in a statement Tuesday that she offered help to both Sanders and Clinton.

"As a longtime political activist with deep ties to our party, I supported all of our candidates for president," she said. "I often shared my thoughts with each and every campaign, and any suggestions that indicate otherwise are simply untrue."

Another email published by Wikileaks this week suggested Brazile gave Clinton's staff a " heads up" on her opponents plans to conduct an education-themed outreach push on social media.