Mr. Parscale, 42, is a frequent presence in Washington. The rare scruffily bearded man in Mr. Trump’s clean-shaven orbit, Mr. Parscale often spends one or two nights a week holding court with vendors and people he describes as “fans” in the lobby of the Trump International Hotel.
Mr. Parscale did not respond to a request for comment on Tuesday, but in an interview with The New York Times in June, he described himself as a “blue-collar kid from Kansas who understood what Trump was saying,” and spoke at length about his devotion to the Trump family.
“I was always the family guy on the campaign,” Mr. Parscale said. “If I saw or heard anything that I didn’t think was good for the family, my loyalty was to the family first.”
In another interview, in August, Mr. Parscale described his role on the 2016 campaign.
“I build the plumbing,” he said. “I changed the plumbing of campaigns, from moving it from TV to digital.”
Kellyanne Conway, Mr. Trump’s campaign manager in 2016 and now a counselor to the president, described Mr. Parscale as an “unbroken thread” from that campaign. “It should surprise no one that family members and a major player who has not come inside the administration would be called upon to redouble that effort for the re-elect,” Ms. Conway said.
Last year Mr. Parscale also took a sizable cut from the Trump campaign. The biggest single expenditure of the $17 million it spent in 2017 was the $5.5 million it paid for digital advertising, nearly all of which passed through firms owned by Mr. Parscale.
Other notable expenditures were $3.1 million on legal expenses, $1.5 million on merchandise — including the red Make America Great Again hats — and nearly $800,000 on Trump properties, including rent on the campaign’s Trump Tower office space. There are no comparable numbers for any previous presidential campaign, because past presidents did not file to run for re-election until well after the halfway point of their first term.
The campaign’s announcement made a point of emphasizing Mr. Parscale’s loyalty to the Trump family. The statement featured quotations from Mr. Kushner and Eric Trump, the president’s middle son, who, along with his wife, Lara, and older brother, Donald Jr., have been active in the campaign.
Mr. Kushner said Mr. Parscale “was essential in bringing a disciplined technology and data-driven approach to how the 2016 campaign was run,” adding, “His leadership and expertise will help build a best-in-class campaign.”
Eric Trump described Mr. Parscale as “an amazing talent” and said he “has our family’s complete trust and is the perfect person to be at the helm of the campaign.”
Still, the choice of Mr. Parscale raised eyebrows because he is not deeply rooted in politics or political strategy. When the campaign gave presentations to reporters in the final two weeks of the 2016 campaign, Mr. Parscale used the website 270towin.com to show the path to victory, as opposed to presenting sophisticated models.
The specifics of Mr. Parscale’s involvement in the Trump campaign, including his tactics to reach voters using social media platforms, has also been of interest to lawmakers on Capitol Hill. Last year, he agreed to meet with the House Intelligence Committee as part of its investigation into Russia’s meddling in the 2016 election.
“I am unaware of any Russian involvement in the digital and data operations of the 2016 Trump presidential campaign,” Mr. Parscale said after he agreed to appear. “The only collaboration I am aware of in the Trump digital campaign was with staff provided to the campaign by Facebook, Google and Twitter.”
President Trump may be itching to hit the campaign trail, where he is happiest, but the White House still has a rail-thin political operation. Despite efforts to hire new staff members, it has struggled for months to catch up to speed. And on Tuesday, the West Wing was set to lose another key aide: Mr. Kushner’s spokesman, Josh Raffel, said he would be departing.
The 2020 campaign announcement, as is common in Trump world, didn’t quite go off without a hitch: For starters, it initially alarmed ethics experts, who said its description of Mr. Kushner as “senior adviser and assistant to the president, and President Trump’s son-in-law,” was in violation of the Hatch Act, which prohibits political activities by government employees. The announcement was later edited to remove “senior adviser.”
“We’ve got a campaign that’s obsessed with campaigning and doesn’t even know what the Hatch Act rules are around Jared Kushner,” Richard W. Painter, who served as a White House ethics lawyer in the George W. Bush administration, said in an interview. “They don’t have any idea what the rules are, and they really don’t care.”
The timing of the announcement also came hours before the disclosure that Mr. Kushner’s security clearance level had been downgraded.