Labour is planning to recast Jeremy Corbyn as a left-wing populist in 2017 to capitalise on the post-Brexit, anti-politics mood sweeping the West.
The Labour leader will make more appearances on television and strategists believe his unvarnished approach could help close the yawning gap in the polls with the Conservatives, a party source confirmed.
The party has suffered two stinging by-election results in recent weeks, slumping from second to fourth in Sleaford and North Hykeham, behind Ukip and the Liberal Democrats, and losing its deposit in Richmond Park.
At a Westminster rally for the NHS on Thursday, Mr Corbyn and shadow health secretary Jon Ashworth criticised Ukip's "divisive" new leader Paul Nuttall, accusing him of wanting to privatise the health service.
It marked a potential pivot in approach for Labour, which faces losing northern Brexit-voting seats to Ukip as immigration continues to play a central role in the Brexit debate.
The issue has proved difficult for the party, with leading figures expressing apparently opposing views.
Last weekend, shadow home secretary Diane Abbott recently appeared to support free movement of EU citizens, saying it was "inextricably linked" to access to the European single market, which Labour is demanding.
But Manchester mayoral candidate Andy Burnham has spoken of the need to end free movement, which he says has had a disproportionate impact on northern de-industrialised communities.
Labour's election co-ordinator Jon Trickett said the party was already placing itself on a war footing in expectation of a snap general election in 2017.
He told the Guardian: "Theresa May has said there will not be a snap election; that doesn't mean there won't be an early election.
"It's our job to be ready. We're ramping up the organisation now. There's a great deal of analytical work going on behind the scenes."
Mr Trickett added: "We need to frame an argument about Britain, its past, present and future - but we will be doing that in a carefully modulated way."