The Labour frontbencher said despite the Conservative Party having a 21 point lead in latest opinion polls, the party had a chance of succeeding.
Put to him whether Labour Party could beat the Tories when they were so far ahead in the polls, the MP for Hayes and Harlington was adamant the party could.
He said: “I think we’ll win the election, I really do. First of all who believes the polls anymore. They got it wrong at the last election, they got it wrong in the referendum, they even got it wrong in America with the Trump election.
John McDonnell said he thought Labour would win the upcoming General Election
We have to be sceptical of these opinion polls but I think what you’ll see in the coming weeks is those opinion polls narrowing as well
“I think we have to be sceptical of these opinion polls but I think what you’ll see in the coming weeks is those opinion polls narrowing as well.
“People didn’t expect this General Election, I don’t think the average member of the public wants this General Election and remember this issue of trust has already tarnished the Prime Minister within the first 24 hours."
Put to him that polls suggested Labour was heading for its worst election defeat since 1935, Mr McDonnell said that was “completely wrong”.
He said: “That’s not the reaction we’re getting on the doorstep. We’ve been campaigning in the local government elections for the last few weeks as well.
Politicians react to Theresa May's snap general election Wed, April 19, 2017
UK Prime Minister Theresa May has announced her intention to hold an early general election on June 8
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Theresa May has called for a snap general election
“We’ve been publishing various policies over the last few weeks and had overwhelming support even in some of the opinion polls as well.”
She said if Labour won the General Election 2017 they would be propped up by the Lib Dems and the SNP, who would be "pulling the strings".
Mrs May urged voters to vote Tory on June 8, in order to deliver a "stronger Britain".