A senior Labour MP said Jeremy Corbyn is fooling himself that the 'Trump-lite' strategy will win the election
The Labour leader last week relaunched himself as a Donald Trump style anti-establishment politician.
Aides told BI that he would be taking a much more "combative" approach to "calling out the injustices and failures of the political and economic establishment."
In a speech at the Fabian Society conference on Saturday, Corbyn echoed Trump in warning that the British people faced a "rigged system" which the elite had used to "line the pockets of their friends."
However, Shadow Health Secretary Jon Ashworth told the conference that while it was right to take a "more vocal" approach, it would not win them the next election.
"Whether we call it Trump-lite, or whatever, I think it is right that we seem to be standing for something while being more vocal in what we believe."
"But I think we sometimes fool ourselves if we think that is enough to bring the Tory walls of Jericho tumbling down."
Ashworth told the conference that Labour would never recover unless it reached out to Conservative voters.
"We will not win elections if we can't persuade that couple in Nuneaton who voted for John Major in 1992 and Tony Blair in 1997 all the way up to 2005 and switched back to voting Conservatives in 2010 and 2015. There is nothing dishonourable in persuading someone who switched to the Conservatives to come back to us."
He added that "Conservative voters are not our enemies they are our neighbours."
The Shadow Health secretary also warned that the party's collapse in Scotland was making them unelectable in the rest of the UK.
"Unless we can show we are competitive in Scotland the Conservatives will run a message saying that we cannot trust Labour in Bolton because a Labour government can only be formed with the support of the Scots nationalists. And so the interests of Banff and Buchan will come ahead of the interests of Bury and Bolton."
Labour MP Stella Creasy told the conference that Labour must avoid a Trump-lite strategy, saying that the party must not become a "pale imitation of the populists."
Creasy told the conference that "I'm not asking you to agree with Nigel Farage. I'm asking you to argue with him."
She also warned that the left had become detached from the culture of the general public.
"Who here watches Mrs Brown's Boys?" she asked.
Just two hands went up in the 1000-seat hall at the Friends House in Central London.
"Well it's the number one viewed television programme in this country. It beat the Queen's speech at Christmas, it won the best comedy of the 21st century and yes the intelligentsia are horrified. They don't get the joke."
She added: "You don't need to be sat in a political conference on a Saturday morning to know that echo chambers are not the reserve of the right."