Theresa May is using “bogus” arguments about Brexit to justify an early election motivated by party-political calculation, Liberal Democrat leader Tim Farron has claimed.

Far from being necessary for the success of Brexit negotiations, the June 8 poll has been called because Tories believe they can capitalise on Labour’s weakness under Jeremy Corbyn, the Liberal Democrat leader said.

Mr Farron was speaking as he visited the Manchester seats of Gorton and Withington, two of a string of Remain-voting Labour strongholds in the North West of England which the Lib Dems hope to snatch from Mr Corbyn’s party.

The Lib Dem leader predicted that Labour will lose “dozens and dozens” of seats on June 8, and said that the only threat to Conservative MPs came from his party.

“There is no doubt whatsoever that Theresa May called this election not for all the bogus reasons she claimed about needing a mandate for Brexit,” said Mr Farron.

“Sadly the Labour Party gave her a mandate for Brexit as they pushed us off a cliff-edge voting for Article 50 without a single condition attached.

“She’s got all she needs if she wants to pursue Brexit, I’m afraid.

Election 2017 result projection with 49 days to go graphic

“She looked across the despatch box and thought ‘I cannot resist the temptation of taking on Jeremy Corbyn and the Labour Party – the most ineffective opposition in inter-planetary history’.”

Mr Farron said the Tories were assuming a “coronation” for Mrs May, despite an approach to Brexit which has “made Nigel Farage look like a moderate”.

But he insisted that Liberal Democrats gave voters “the opportunity to change the direction of this country” by electing MPs who will hold back the “disastrous” drive to take Britain out of the single market.

“Nobody thinks the Labour Party will gain a single seat from the Conservatives. They will lose dozens and dozens,” he said.

“The only route through which Theresa May has a single thing to be afraid of is from the Liberal Democrats, and she has every reason to be afraid of the Liberal Democrats because we will stand very clearly on a passionate platform of being in favour of an open, tolerant, united country, where everybody is equal and everybody has the ability to make their own choices and decide their own future.”

The Liberal Democrats are targeting Remain-voting Labour seats in the North of England where voters feel “betrayed by Jeremy Corbyn’s support for a divisive hard Brexit”, Mr Farron said.

Ten of the 100 seats with the highest Remain vote last June are in the North of England, two of which are currently held by the Liberal Democrats and seven by Labour.

As well as Gorton and Withington, these include Liverpool Riverside, Sheffield Central, Leeds North West, Liverpool Wavertree, Sheffield Hallam, Manchester Central, Leeds North East and Altrincham & Sale West.

Mr Farron said: “From Manchester to Newcastle, even lifelong Labour supporters are feeling let down by a party that has betrayed their values and taken their votes for granted. This election is a chance for them to change direction of the country.