President-elect Donald Trump has used WikiLeaks founder Julian Assange to cast doubt on the US intelligence community's case that Russia was behind the hacking of the Democratic National Committee (DNC) ahead of the 2016 election.
He suggested that the DNC is to blame for the hacking of its computers and emails, including those of top Hillary Clinton adviser John Podesta.
Mr Trump continued his tweetstorm on Wednesday by arguing the DNC did not have a "hacking defence" and questioning why the Democratic Party had not responded "to the terrible things they did and said".
He appeared to be referring to information in the DNC emails that was made public and led to the resignation of the DNC chairwoman and other officials.
"Julian Assange said 'a 14 year old could have hacked Podesta' - why was DNC so careless? Also said Russians did not give him the info!" Mr Trump tweeted early on Wednesday.
It was a striking spectacle for the incoming president to give credibility to Mr Assange, whose organisation has been under criminal investigation for its role in classified information leaks.
Mr Assange has said his source for the hacked emails WikiLeaks published during the campaign was not a government, but his assertion has left open the possibility they came from a third party.
The American intelligence community and Republicans and Democrats on Capitol Hill insist that Russia was behind the hacks, but Mr Trump has repeatedly dismissed that allegation, challenging the intelligence experts who will help him make the weightiest possible decisions once he becomes president on January 20.
Mr Trump has insisted that the government does not really know who is behind the attacks.
He has said he will release more information this week.
In a series of tweets on Tuesday and early on Wednesday, Mr Trump wrote without evidence that the timing of an upcoming intelligence briefing on suspected Russian interference in the 2016 election had been delayed.
"Perhaps more time needed to build a case."
"Very strange!" he wrote, using quote marks around the word "intelligence".
Mr Trump's tweets, in line with repeated criticism of his nation's intelligence leaders, caused confusion among intelligence officials, who said there was no delay in the briefing schedule.
The fresh clash came as Mr Trump took further steps to fill his cabinet and key White House positions, with his attention shifting towards the challenges of governing.
Mr Trump's plans for repealing President Barack Obama's signature healthcare law are expected to be the focus as Vice President-elect Mike Pence and secretary of state choice Rex Tillerson meet top Republicans on Capitol Hill on Wednesday.
Mr Pence issued a direct challenge to Washington Republicans on Tuesday, saying: "The president-elect has a very clear message to Capitol Hill. And that is, it's time to get to work."
Mr Trump signalled he would not bless all of the party's priorities on Capitol Hill, openly questioning the timing of the House Republican push to gut an independent ethics board just as the new Congress gathered. The House Republican party later dropped the effort.
The president-elect promised late on Tuesday to hold his first formal news conference since his November 8 election victory next week in New York.
He has already waited longer than any other president-elect in the modern era to hold his first exchange with journalists. Most have held such events within days of their elections.
It was unclear if the news conference would be the venue for his delayed announcement on how he plans to avoid potential conflicts of interest involving his businesses after taking office.
Transition officials said multiple topics could be covered, but would not specifically say whether they included Mr Trump's businesses.
Mr Trump was supposed to detail the arrangements at a mid-December news conference, but postponed the event.
His cabinet nearly full, Mr Trump also picked a handful of new White House aides.
Omarosa Manigault, a contestant from the first season of The Apprentice, is expected to focus on public engagement in the White House.
Mr Trump also hired Rick Dearborn as a deputy chief of staff and Marc Short as White House legislative director. Both previously served in chief of staff positions on Capitol Hill.
Mr Trump spent time interviewing prospects for the department of veterans affairs as well, including Leo MacKay, a senior executive at a military contractor who previously served in the VA under President George W Bush.