Jeremy Corbyn is appealing to supporters in two crunch by-elections to back Labour and "send a message" to the Government rejecting Conservative austerity cuts.
Speaking at Labour's local government conference in Warwick, Mr Corbyn will say the polls on Thursday in Copeland and Stoke-on-Trent Central give voters a chance to say they have had enough of cutbacks to health and social care.
The twin by-elections - caused by the resignations of sitting Labour MPs Jamie Reed and Tristram Hunt - represent Mr Corbyn's most difficult electoral challenge so far.
With Labour trailing in the polls, the Conservatives are hoping to make a rare by-election gain for a governing party and pull off victory in Copeland.
The Cumbrian constituency is heavily reliant economically on the Sellafield nuclear processing facility and Mr Corbyn's past opposition to nuclear power is viewed with suspicion by many voters.
In Stoke – which voted strongly for Brexit in last year's referendum – the main challenge is expected to come from Ukip where party leader Paul Nuttall is standing.
In his speech, Mr Corbyn will attempt to rally supporters with a call to reject the of attempts of the parties of the right to sow division in communities.
"Ukip's politics of hate will not save children's centres. Hatred won't build homes. It won't create jobs, and it won't fund health and social care. It won't bring our people dignity or bring our communities together," he will say.
"But that's true of the Tories too. When politicians of the right have no solutions, they find a scapegoat. They try to divide and set people against each other.
"Voters have a chance to tell the Government that they've had enough of their damaging cuts to health and social care, and their disregard for human life and dignity.
"Our job, as the Labour Party, isn't to find a vulnerable community to blame. It is to unite people together to build a better world."