Number 10 has refused to comment on the phone call between Trump and Theresa May.
Momentum claimed to have reached 30% of UK Facebook users with viral videos.
Shadow Chancellor says it is important to respect the result of the EU referendum.
Tory MP Dominic Raab attacked former Chancellor for his 'unprofessional' remarks about the PM.
"This election wasn't just about Brexit – there was something very different about it," left-winger said.
UK foreign secretary has publicly thrown his support behind the prime minister.
Downing Street gaffe comes after Theresa May's top aides - Nick Timothy and Fiona Hill - quit.
Intervention comes after the Conservatives gained 12 seats north of the border at the election.
Academic wrongly said Jeremy Corbyn's Labour Party would not get more than 38% of the vote.
Christina Abada was captured by the murderous terrorist group at just three-years-old in 2014.
UK prime minister's closest advisers quit over Conservative failure to win general election
Exclusive: Senior Ukip source tells IBTimes UK that a Farage return is unlikely.
Comes as top pro-Brexit Conservative MEP tells IBTimes UK that 'genuine stability' is needed.
Who are Nick Timothy and Fiona Hill – May's 'arrogant' aides who stood down after election disaster?
With the Brexit talks looming, Prime Minister Theresa May has lost her two top advisers.
UK has been left with a hung parliament.
'Strong and stable' British prime minister left 'weak and wobbly' after disastrous election.
"People have said that they've had quite enough of austerity politics," the Labour leader said.
'The business community is about to have a remarkable few hours,' the IoD told IBTimes UK.
Left-winger drew hundreds of supporters to north London just hours before the election polls opened.
Senior party source tells IBTimes UK of plan on eve of the UK general election.
Prime minister made a "right pig's ear of it", Communication Workers' Union chief Dave Ward said.
Ukip leader said he would only endorse a handful of Labour candidates at the general election.
Top Liberal Democrat says families across the UK will face a 'Brexit squeeze' thanks to the split.
Survation says there is now just one point between Labour and the Conservatives as the 8 June vote looms.
Corbyn said May should quit Number 10 after overseeing cuts to police numbers in the Home Office.
The former Number 10 adviser made the intervention ahead of the general election.
Paul Oakden spoke to IBTimes UK about Ukip's chances ahead of the 8 June vote.
Major parties have suspended national campaigning for the day following atrocity.
IBTimes UK travels to Boston, Lincolnshire, where immigration continues to be a major issue.
Labour leader said he would attempt to change the US president's mind over a drink in Number 10.