Jon Lansman, who founded the Jeremy Corbyn support group, is one of three new members of the National Executive Committee. Seizing control of the committee will give Mr Corbyn's backers near complete control of Labour and prompt growing fears of de-selection among moderate MPs.
Mr Corbyn acknowledged Britain's relationship with the USA was crucial "because it is such a huge military and economic power", but said ties with the EU, India and China were also "very important". Mr Lansman received 65,163 votes and Rachel Garnham, a member of Labour's national policy forum, received 62,982.
Cross-dressing comedian and pro-European Union centre-left activist Eddie Izzard was the highest placed of the six losers, garnering just over 39,500 votes for his platform of increasing diversity in the party.
In his campaign, Mr. Lansman said he meant to use his new position on the NEC change how the Labour Party operates, to make it more grass-roots and democratic.
Ms Dar - who topped the poll with 68,388 - tweeted: 'Delighted, honoured & humbled to be elected onto the National Executive Committee (NEC) of the Labour Party.
The successful trio were also backed by the Campaign for Labour Party Democracy which seeks more power for party members and more working class election candidates.
When long-term Labour campaigner Izzard announced his intention to stand in October, he referred to his personal challenges of coming out as a transvestite and said: 'I can break down barriers and make the Labour party more welcoming to groups who often feel isolated or excluded from taking part in the political process.
MODERATE Labour MPs could quit and stand as independents against the party if they are booted out of their seats by the hard left.
Also missing out in today's results were Johanna Baxter, Gurinder Singh Josan, Nick Donovan, Nicola Morrison and Sarah Taylor. The case for a complete break from the European Union was no longer being made, even by pro-Brexit MPs in parliament, he said.
'The new establishment has a big responsibility to ensure a broad church Labour party that can use all the talents of Labour to stop a hard Brexit and win the next election, not focus on internal rules changes.
However he told Julia this morning that he " "wouldn't advocate Momentum trying to replace all Labour MPs with Momentum MPs".
The results were published on the same day Nicola Sturgeon warned that a no deal Brexit could lead to a 8.5 per cent reduction in Scottish GDP by 2030.