Washington (CNN) Donald Trump's dismissal of US intelligence about Russian election meddling has deeply alarmed the White House, prompting a new and combative approach to the President-elect that's caused rifts between the incoming and outgoing administrations.

Even as President Barack Obama seeks to maintain an amicable relationship with Trump in an attempt to influence his successor's agenda, the public spat between aides over Russia's hacking has turned into the type of bitter back-and-forth the White House initially sought to avoid in the days immediately following the election.

Obama is also expected to address the Russian hacking allegations during his final planned news conference of the year from the White House on Friday at 2 p.m. ET.

Also fueling the rhetoric: Democrats' complaints the White House was slow in confronting Russia's hacking in the final days of the presidential campaign, a claim the White House disputes.

The latest volley came from former Trump campaign manager Kellyanne Conway who said Friday that Obama and Democratic presidential nominee Hillary Clinton could bring a ceasefire between them if they "actually love the country enough."

"If you want to shut this down and you actually love the country enough to have the peaceful transition in our great democracy between the Obama administration and the Trump administration, there are a couple people in pretty prominent positions -- one is named Obama, one is named Hillary Clinton, since his people are trying to fight over her election still, they could shut this down," Conway told Fox News.

On Thursday, White House Press Secretary Josh Earnest escalated his post-election criticism of Trump, insisting it was plainly obvious to the Republican's team that Russia was interfering in the US election to bolster their chances of victory.

He dismissed the President-elect's response as unserious, and encouraged Trump to answer questions about the hacking instead of questioning US intelligence.

"It's just a fact -- you all have it on tape -- that the Republican nominee for president was encouraging Russia to hack his opponent because he believed that that would help his campaign," Earnest said, calling it a "basic fact" of the presidential contest.

"I don't know if it was a staff meeting or if he had access to a briefing or he was just basing his assessment on a large number of published reports, but Mr. Trump obviously knew that Russia was engaged in malicious cyberactivity that was helping him and hurting Hillary Clinton's campaign," Earnest said.

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Trump tore into Earnest while speaking at a rally Thursday night in Hershey, Pennsylvania, calling him a "foolish guy."

"He could say, ladies and gentlemen today we have totally defeated ISIS and it wouldn't sound good, OK? All right?" Trump said.

Trump didn't let his criticism of Earnest undo the largely positive comments he has made in recent weeks about Obama. Instead, Trump suggested that Earnest could be "getting his orders from somebody else," though he did not elaborate on whom he believes is breathing orders into the White House press secretary's ear.

David Axelrod, a former senior adviser to Obama, said it was "highly unlikely" Earnest was scaling up his hits on Trump without the President's approval.

"A press secretary doesn't go out and make statements like that on an unauthorized basis," said Axelrod, now a CNN senior political commentator.

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Tensions rising

The public acrimony between the two camps has escalated in recent weeks, far exceeding tension between Obama's transition team and President George W. Bush's administration in 2008.

It's a distant cry from the days immediately following Trump's victory, when Obama and his aides were careful to avoid repeating their campaign trail criticisms of Trump, insisting the transition of power proceed professionally and without political bias.

White House officials said they were looking to establish a clear message of calm and continuity at a moment of deep concern about Trump's preparation for the job and his foreign policy priorities.

Obama and some top aides were said to be irritated when reports emerged that Trump seemed stunned at the scale of the presidency during his Oval Office meeting on November 10 -- and they were concerned it could lead to him turning away from Obama, who remains intent on not antagonizing Trump as he continues phone consultations with his successor.

Conversations between the two men continue, including last weekend, and both sides insist the actual work of transferring power is proceeding professionally.

But in public, the spat over Russia has revealed a deep divide.

The President-elect's dismissal of US intelligence pinning Russia to the hacking was "materially different" from Trump's other bombastic statements, according to one White House official who spoke anonymously to describe internal thinking. It motivated the White House to alter its approach.

Obama administration officials viewed Trump as waging an outright attack on the intelligence community, the official said, and worried about the implications of his words on national security going forward.

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In his briefings, Earnest has resumed tying Trump to Russia, a staple of Obama's own campaign stump speech.

"It was the President-elect who, over the course of the campaign, indicated that he thought that President Putin was a strong leader," he said on Monday, continuing with a litany of examples meant to demonstrate a tight alliance with Moscow. "His campaign didn't make any effort to obscure this."

Despite an initial reluctance to withhold comment on Trump's cabinet picks, he's tied the President-elect's selection as secretary of state, ExxonMobil CEO Rex Tillerson, to Trump's approach to Russia.

"The President-elect indicated his intent, if elected President, to pursue warmer relations with Russia," he said Tuesday. "What better way to do that than to choose somebody who has been awarded the Order of Friendship by Vladimir Putin to be your secretary of state?"

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Earnest defends White House

Earnest has also found himself rebutting accusations from Democrats that the administration acted slowly to identify Russia as the hacking culprit.

Earnest has argued that pushing the intelligence community to offer an assessment sooner would appear like political interference. And he's claimed Moscow's actions and intentions were clear, including to the Republican nominee.

"It benefited the Trump campaign. And it hurt the Clinton campaign. That's why the Republican nominee was hoping that they would do more of it," he said Wednesday. "That's why his staffers were hoping they would do more of it. That is why in the days leading up to election day, the Republican nominee himself was encouraging people to check out WikiLeaks."

The rhetoric reflects a more combative transition than Obama underwent in 2008, though some tensions existed between his team and Bush's outgoing administration over economic issues.

Jim McGrath, a close aide to the Bush family, tweeted that the press secretary in the final days of George W. Bush's presidency was not so critical of the then-President-elect.

"Remember when @DanaPerino trashed Barack Obama from WH podium after George W. Bush pledged full cooperation w the transition? Me neither," he tweeted.