WASHINGTON — President-elect Donald Trump shook up his transition team Friday as he plunged into the work of setting up his administration, elevating Vice President-elect Mike Pence to head the operations. The move, one of the first key decisions as Trump pivots from campaigning to governing, amounted to a demotion for New Jersey Gov. Chris Christie, who had been running the Republican’s transition planning for months.

On the heels of Trump’s upset victory this week, his team has begun to embark upon building a government, an enormous undertaking that likely requires Trump to alter his hands-on management style and consider going outside his small, insular group of loyalists. He has been scrambling to identify people for top White House jobs and Cabinet posts, a herculean task that must be well in hand by the time Trump is inaugurated on Jan. 20.

For Trump, who ran on a pledge to “drain the swamp” of Washington insiders, the team is strikingly heavy on those with long political resumes.

And another apparent contradiction emerged Friday as Trump, who repeatedly vowed to repeal the Affordable Care Act “on day one,” said he would be open to maintaining portions of President Barack Obama’s signature legislative achievement.

In a statement Friday, Trump said Pence would “build on the initial work” done by Christie.

“Together, we will begin the urgent task of rebuilding this nation — specifically jobs, security and opportunity,” Trump said.

Christie was a loyal adviser to Trump for much of the campaign, offered a key early endorsement and came close to being the businessman’s pick for running mate. But Trump ultimately went with Indiana Gov. Pence, a former congressman with Washington experience and deep ties to conservatives.

In a statement, Christie said he was “proud to have run the pre-election phase” of the transition team and thanked Trump for the “opportunity to continue to help lead.”

Christie will still be involved in the transition, joining a cluster of other steadfast Trump supporters serving as vice chairs: former House Speaker Newt Gingrich, retired neurosurgeon Ben Carson, retired Lt. Gen. Michael Flynn, former New York City Mayor Rudy Giuliani and Alabama Sen. Jeff Sessions.

In addition, three of Trump’s adult children — Don. Jr., Eric and Ivanka — are on the transition executive committee, along with Jared Kushner, Ivanka’s husband. Kushner played a significant role in Trump’s campaign and was spotted at the White House Thursday meeting with President Barack Obama’s chief of staff.

The children’s inclusion raises questions about the role the Trump family will play in the White House — as well as Trump’s ability to sever ties between the administration and sprawling family business — after the celebrity businessman repeatedly said during the campaign that his grown children would not follow him to Washington and instead run the Trump Organization.

Trump’s remarks about the Affordable Care Act also raised some eyebrows Friday. After speaking with Obama at the White House the day before, Trump said he was considering keeping the clause that allows children to stay on their parents’ insurance policies. In a separate interview, he said, “it happens to be one of the strongest assets.”

He has previously said he may keep the prohibition against insurers denying coverage because of patients’ existing conditions.

He also said that he wants “a country that loves each other” but said he did not regret his incendiary rhetoric during the campaign.

By appointing Pence, Trump became the first incoming president since at least Jimmy Carter to use his vice president-elect to run his transition team.

Trump and Christie grew apart through the last stretch of the campaign. The governor became increasingly frustrated that Trump wouldn’t listen to his advice, particularly over the response to the release of a video in which the businessman is heard making predatory comments about women.

Christie is also facing calls for impeachment in New Jersey following the conviction of two former aides in the George Washington Bridge lane-closing trial. Christie has denied any knowledge of the lane closures until weeks or months after they occurred in September 2013.

The governor was notably absent from the steady stream of advisers entering Trump’s eponymous skyscraper in New York for meetings Friday. Among the first decisions facing the president-elect is whom to choose as chief of staff, a key post that will set the tone for Trump’s White House and be a key conduit to Capitol Hill and Cabinet agencies.

Trump is said to be considering Steve Bannon, his campaign chairman and a conservative media executive, and Republican National Committee Chairman Reince Priebus for the role. Neither has significant policy experience, though Priebus is well-liked in Washington and has ties with key lawmakers.

Kellyanne Conway, Trump’s campaign manager, is also said to be in the mix for a senior job.

Conway is a veteran Republican pollster who formed a strong rapport with the candidate after taking the helm of his campaign in the general election.

Giuliani, who emerged as Trump’s frequent travel partner and close aide during the campaign’s stretch run, is on the short list for several positions, including attorney general.

“Donald has been my friend for 28 years,” Giuliani said Friday after leaving a meeting at Trump Tower. “I can see already how he is going to be a great president and I am glad I can play a small role.”