Sir Keir Starmer has claimed that Gorton and Denton will “descend into hostility” if Reform UK wins a crucial by-election in the seat later this week.
The Prime Minister said community tensions would rise if Nigel Farage’s party gained a ninth MP in the Greater Manchester constituency.
Voters in Gorton and Denton will go to the polls on Thursday in what is expected to be a three-way contest between Labour, Reform and the Greens.
Sir Keir has stepped up his attacks on Reform and Mr Farage in recent months, accusing them of “racist” policies and claiming that they would tear Britain apart.
Making his first appearance on the by-election trail on Monday afternoon, the Prime Minister insisted the contest would be a two-horse race between his party and Reform.
He said: “The battle here is that basic battle between a party that wants to bring our communities together, to make sure that everybody in this constituency has their voice heard in Parliament through their brilliant Labour candidate, or a party that couldn’t really care less where the constituency is.
“That is not the politics of this constituency. That is not the politics of this country.
“And we must be in this fight, fighting for all the people that will be affected by decisions made here on Thursday and making sure that they have the hope to go forward, that better support from a Labour Government and to make sure that we do not descend into hostility, which would follow a Reform win.”