Incoming Trump administration members Sean Spicer, communications director, left, and Chief of Staff Reince Priebus in Washington on Jan. 13. (Jonathan Ernst/Reuters)

President-elect Donald Trump entered the week of his inauguration fending off questions about the legitimacy of his presidency even as he promised to unite the nation as its new leader.

Taking its cue from Trump, his administration-in-waiting came out swinging this weekend against criticism from all corners. His aides went on the attack against the Democratic Party and Rep. John Lewis (D-Ga.), the civil rights icon who questioned the legitimacy of Trump’s claim to the White House. And a top aide issued a pointed warning to the head of the Office of Government Ethics to “be careful” after he publicly called for Trump to make a cleaner break with his business interests. Furthermore, Reince Priebus, the incoming White House chief of staff, piqued the news media’s interest by acknowledging that there had been discussion about moving press briefings out of the White House to accommodate larger crowds.

Trump’s top aides pushed back hard on the notion that Trump’s presidency was somehow not legitimate — a charge that stems from the allegation that Russia meddled in the elections — with Priebus describing Lewis’s charges as “insanity” and “incredibly disappointing.”

“I think President Obama should step up,” Priebus told ABC’s “This Week.” “I think the administration can do a lot of good by telling folks that are on the Republican side of the aisle, ‘Look, we may have lost the election on the Democratic side, but it’s time to come together.’ ”

(Bastien Inzaurralde/The Washington Post)

Vice President-elect Mike Pence asserted Trump’s right to “defend himself” against the suggestion that he is not a legitimate president, even coming from an “icon” such as Lewis. And he criticized Lewis for refusing to attend Trump’s inauguration.

“To hear John Lewis, a man that I served with, that I respect, question the legitimacy of the election and to say that Donald Trump will not be a legitimate president is deeply disappointing to me. And also to hear that he was not going to attend the inauguration this Friday — I hope he reconsiders both statements,” Pence said on CBS’s “Face the Nation.”

The combative stance comes five days before Trump will take the oath of office and address a bitterly divided nation.

“For many years our country has been divided, angry and untrusting. Many say it will never change, the hatred is too deep. IT WILL CHANGE!!!!” Trump tweeted Sunday afternoon.

On Saturday, Trump was widely criticized for responding to Lewis with tweets that accused the congressman of being “all talk” and “no action, no results.” Lawmakers in both parties pointed to the arrests and physical beatings that Lewis withstood as a leader in the civil rights movement as evidence to the contrary.

The incident, which came at the start of the Martin Luther King Jr. Day holiday weekend, might serve only to deepen the distrust of Trump among African Americans. National exit polling from the election found that 91 percent of black voters viewed Trump unfavorably.

Trump also poured salt on old wounds for Democrats who argue that his long history of doubting President Obama’s citizenship was a racist effort to delegitimize the country’s first black president.

“What [Democrats] are right about is to talk about the racist past of Donald Trump,” Sen. Bernie Sanders (I-Vt.) said Sunday on ABC’s “This Week.”

Transition officials deflected questions about Trump’s years-long refusal to accept that Obama is a natural-born American citizen, calling it “old news.”

Priebus said Sunday that questions about Obama’s birth have “been resolved for at least two years in Donald Trump’s mind” and distinguished between questioning Obama’s citizenship and accepting the results of the election.

“This Week” host George Stephanopoulos corrected Priebus, noting that Trump continued to raise questions about Obama’s eligibility well into his own presidential campaign.

“That’s not the point. The point is not where Barack Obama was born,” Priebus said.

Priebus took a similarly bellicose stance against Walter Shaub Jr., the director of the Office of Government Ethics.

Shaub has publicly criticized Trump’s transition team for rushing his nominees’ ethics reviews, and he called on Trump to divest his business assets to avoid conflicts.

The comments prompted Rep. Jason Chaffetz (R-Utah), chairman of the House Oversight Committee, to call for Shaub to testify before Congress.

Priebus said on ABC that Shaub “ought to be careful” because he was “becoming extremely political.” Priebus claimed the ethics chief supported Hillary Clinton during the campaign, and he cited concerns about tweets the ethics office directed at Trump last month. “I’m not so sure what this person at government ethics, what sort of standing he has anymore in giving these opinions,” he said.

The comments and the prospect of a congressional investigation were taken as a thinly veiled threat to Shaub, a political appointee named by Obama in 2013 to a five-year term.

“Why is Congressman Chaffetz investigating Walter Shaub for doing his job, George, for speaking so courageously?” Norm Eisen, a former Obama ethics czar, said on ABC. Eisen on Twitter called Priebus’s comments “shocking, ­mafia-style THUGGERY.”

Priebus also signaled that the news media may be seeing changes during the Trump administration. To allow for “more press coverage from around the country,” the incoming chief of staff told ABC that the initial press briefings may be moved from inside the White House to the nearby Eisenhower Executive Office Building. He did not mention evicting media members from their workspace inside the White House and near the offices of the president and vice president, despite reports to the contrary.

“This is all a distraction, and it’s all part of a narrative to delegitimize the election,” Pence said on “Fox News Sunday.” “The American people see right through it.”