Former Vice President Joe Biden Joe BidenFormer Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick Bloomberg rolls out M ad buy to boost Biden in Florida MORE's presidential campaign has hired a longtime Obama White House aide to be a senior adviser and its chief operating officer, sources tell The Hill.

Maju Varghese will help the Biden campaign "hum and work a little more seamlessly," one source said.

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"He's a grown-up," the source added. "He understands how things work."

Varghese, a longtime Washington operative, served as an assistant to former President Obama for management and administration and as deputy director of advance at the White House, where he managed day-to-day operations.

He will now bring that experience to the former vice president's campaign.

"Many of the Biden staff he'll manage worked with or for him in the Obama White House," a second source explained.

Varghese has "very deep experience," according to one longtime Obama aide who added that he's got "great operational experience and helps professionalize the operation."

Biden remains the front-runner in the crowded 2020 Democratic field. A Morning Consult poll out this week shows the former vice president leads the field by 12 points.

Still, Biden has faced some stumbles in recent weeks after he made a string of verbal flubs.

Some allies have suggested to the campaign that Biden have more down time between events to help minimize the gaffes. Other allies have said that Biden needs more people around him who are familiar with how he operates and know how to run a modern day campaign.

Varghese will "help in more ways than one," one Biden ally said. "He's a good addition."