Senior White House advisor Anita Dunn is leaving her post next week to guide a massive political action committee that is supporting Vice President Kamala Harris' presidential campaign against former President Donald Trump, according to a senior White House official.

Dunn, who has been a trusted ally of President Joe Biden's for years, will advise Future Forward, a PAC that recently launched a $50 million advertising campaign in support of Harris, the official confirmed. The news was first reported by The Washington Post.

In a statement, Biden praised Dunn as "tough and tested."

"I deeply value her counsel and friendship and I will continue to rely on her partnership and insights as we finish the job over the next six months," said Biden.

"It's been an honor and privilege to serve in this White House, with this President and this team, during this transformational term. I am grateful to President Biden and Vice President Harris for their leadership and giving me the opportunity to be part of what they have accomplished for the American people," said Dunn in a statement to NBC News.

Dunn's departure from the White House to help Harris is a sign that Biden's closest advisors are gearing up to help the vice president try to defeat Trump.

Dunn is a veteran political player and was an advisor to Biden when he ran for president against Trump in 2020. She joined the Biden White House in 2021, before leaving briefly and then returning in 2022 to advise the president.

Prior to her role with Biden, she was a managing director at consulting giant SKDK and was a close advisor to former President Barack Obama.