CNN  — 

Joe Biden has hired Jen O’Malley Dillon as his new campaign manager in a shake-up of top-level staff as the former vice president looks to close out the Democratic primary against Vermont Sen. Bernie Sanders and prepare for the general election.

O’Malley Dillon, a former top Barack Obama campaign aide who last year managed Beto O’Rourke’s presidential bid, had been helping Biden’s campaign since the Nevada caucuses, where Biden began his rebound after disappointing showings in Iowa and New Hampshire.

She replaces Greg Schultz, who is remaining with the campaign in what’s being described as an important role that hasn’t fully been defined.

Visit CNN’s Election Center for full coverage of the 2020 race

Anita Dunn, who Biden had elevated above Schultz and was handed final decision-making authority on the campaign weeks ago, will remain on as a senior adviser.

The decision to bring O’Malley Dillon aboard underscores the urgency now facing Biden as he pivots to a likely general election contest with President Donald Trump. The Biden campaign, for most of the last year, has been underfunded and overseen by longtime aides to the former vice president, who now are scrambling to expand to be competitive with the massive operation Trump has been building.

“They need to ramp up and ramp up now,” a longtime Obama adviser told CNN, speaking on condition of anonymity to avoid being seen as criticizing the Biden team. “The Trump campaign has a huge head start.”

The hiring of O’Malley Dillon is also designed to professionalize the Biden campaign as well as send a message to Democratic donors and supporters that the former vice president is adding structure to his team. She is the first of several high-level strategists who will be joining the Biden campaign headquarters in Philadelphia in the coming weeks, people familiar with the matter say.

Biden’s campaign has received an influx of resumes and interest from aides to his former Democratic primary rivals and is in the process of building out every operation, Dunn told CNN on Wednesday. But multiple sources said it could take time for the campaign to work through its senior staff-level changes because it also faces decisions about how Biden will move forward amid concerns about coronavirus.

O’Malley Dillon was a deputy campaign manager for Obama’s reelection effort in 2012 and is seen as one of the party’s sharpest data experts. Her hiring could also open the door to more former Obama staffers joining the Biden campaign.

O’Malley Dillon, a founder of the Washington firm Precision Strategies, has also worked as a political consultant for Canadian Prime Minister Justin Trudeau. Her bid as campaign manager for O’Rourke was short-lived, but she is one of the most respected operatives in Democratic politics. She is also a former executive director of the Democratic National Committee and worked on John Edwards’ 2004 and 2008 presidential campaigns.