Jennifer O’Malley Dillon, Biden’s Campaign Manager, Will Tackle Another Difficult Job

[Follow our live coverage of the Biden inauguration.]

Jennifer O’Malley Dillon had barely started the job when she shut it all down.

Just two days after Ms. O’Malley Dillon was named President-elect Joseph R. Biden Jr.’s campaign manager, her operation went entirely remote, an early concession to a virus that would come to define the entire election.

Ms. O’Malley Dillon, 44, found herself taking on tasks never before handled by a campaign, like setting up testing protocols to keep her staff and a 77-year-old candidate safe from a deadly virus, while also trying to win a race that her party viewed as an existential battle for the future of the country. Her campaign battle cry, according to friends and former staff members: “We can do hard things.”

Ms. O’Malley Dillon will now tackle another difficult job when she assumes the role of deputy chief of staff in the new Biden administration. A stalwart of Democratic politics, she has never worked in the White House and is a rare new admission into Mr. Biden’s tight circle of trusted aides. Expected to be charged with managing White House operations — a job that has traditionally included logistics, administration and making sure the place runs on time — Ms. O’Malley Dillon will join an administration facing a raging pandemic, economic instability and a fiercely divided country.

“She’s a fixer,” says Christina Reynolds, an old friend of Ms. O’Malley Dillon and a vice president of Emily’s List, a leading Democratic women’s group. “She deals with the situation that you live in, not the situation you wish you had.”

The daughter of a school superintendent and an elementary-school teacher, Ms. O’Malley Dillon spent more than two decades winding her way through Democratic Party politics. In 2003, she worked on Senator John Edwards’s first presidential campaign, where she met her husband, Patrick Dillon. (Their first date: the classic political stomping ground of the Iowa State Fair.)

In 2008, she ran the battleground-states operation for Barack Obama’s presidential effort and became the executive director of the Democratic National Committee after the election. Four years later, she was the deputy manager of Mr. Obama’s 2012 re-election campaign before starting a public relations firm. Her clients include Prime Minister Justin Trudeau of Canada and Stacey Abrams, a former minority leader of the Georgia House who was briefly considered as a running mate for Mr. Biden.

Considered one of the top organizing talents in her party, Ms. O’Malley Dillon was sought out for advice by various Democratic primary candidates before joining the campaign of former Representative Beto O’Rourke of Texas.

When Mr. O’Rourke quit the race, Anita Dunn, a longtime Biden ally, asked Ms. O’Malley Dillon to transform what was then a shoestring Biden primary campaign into what became a general election juggernaut. Though she had little of a relationship with Mr. Biden, the two found common ground in their Irish Catholic roots. He’s my people, one of Ms. O’Malley Dillon’s friends recalled her saying of Mr. Biden.

During the campaign, she ignored the complaints within her party over Mr. Biden’s light travel schedule during the pandemic, but also charted a conventional approach to winning back the White House by focusing on the traditionally Democratic states that eluded the party in 2016 — Pennsylvania, Michigan and Wisconsin.

Working from her suburban Washington home, Ms. O’Malley Dillon conducted late-night meetings from the seat of her Peloton bike and prepared her staff for the rollout of the vice-presidential pick with her 8-year-old twin girls and 3-year-old son just offscreen.

With Mr. Biden’s victory, Ms. O’Malley Dillon became the first woman to manage a victorious Democratic presidential campaign. The only other woman to manage a winning presidential campaign was Kellyanne Conway, who spent three months at the head of Donald J. Trump’s operation in 2016.

“Not only did Jen win a campaign against an incumbent president, which has only happened a handful of times over the last 200-plus years, she secured the highest popular vote ever in the midst of a global pandemic,” said Stephanie Cutter, a Democratic strategist and co-founder of Ms. O’Malley Dillon’s firm. “That’s a feat that will go down in the history books.”