Donilon, senior adviser at the White House, is expected to play a central role in the campaign's messaging and paid media strategy, while O'Malley Dillon, deputy chief of staff, will oversee the organizing and execution of the campaign's path to the 270 electoral votes needed to win, according to a source familiar with the plans, who provided no further explanation.

"Mike and Jen were essential members of the senior team that helped President Biden and Vice President Harris earn the most votes in American history in 2020, and we're thrilled to have their leadership and strategic prowess focused full-time on sending them back to the White House for four more years," campaign manager Julie Chavez Rodriguez said in a statement.

Several Democrats, including former President Barack Obama, have questioned Biden's reelection strategy and encouraged him to shift people and decision-making from the White House to his headquarters in Wilmington.

"I’m thankful to Mike and Jen both for their service in the White House these last three years, and I am grateful that in rejoining the campaign, they are stepping up one more time to ensure we finish the job for the American people," Biden said in a statement.

Trump won New Hampshire's Republican presidential primary election on Tuesday, Edison Research projected, moving closer to a likely Nov. 5 rematch with Biden even as his only remaining rival, former U.N. Ambassador Nikki Haley, vowed to soldier on.

Edison projected Biden would win the New Hampshire Democratic primary based on write-in votes, after he declined to appear on the ballot due to a dispute with the state about the election's timing.

Biden and Vice President Kamala Harris - in a bit of counterprogramming, traveled Tuesday to Virginia for a campaign event on abortion, an issue that has proven to drive voters to the polls to oppose conservative measures.