Nigel Farage has vowed to target the five million Labour voters who backed Leave in the referendum.
It comes as the Brexit Party leader confirmed he intended to run candidates in more than 600 constituencies at the general election.
Addressing the cheering candidates at a rally in Westminster he criticised Labour’s “betrayal” in backing a second referendum and attacked Boris Johnson’s Withdrawal Agreement as “not Brexit”.
“Do I detect a group of people who don’t care what the mainstream media say, don’t care what the Tory or Labour Party say but want to stand up for the 17.4 million people?” he said.
“I want the country to know the sheer extent of Labour's betrayal. I want the country to know that this new EU treaty is not Brexit and if it goes through, we will never get independence.”
The Brexit Party would now be focusing, he said, on those Leave-voting Labour constituencies who were represented by pro-Remain MPs.
"Those five million are the most vulnerable group of voters to the Brexit Party in this country," he said.
"I will be out in those Labour constituencies. I'll be in the East Midlands, I'll be in South Wales. I'll be in the North East. I want the country to know the sheer extent of Labour betrayal."
Mr Farage described it as "absolute tosh" that the decision to stand candidates in almost every UK seat could cost the Tories a majority and possibly put Brexit at risk.
Referencing UKIP’s performance in 2015, he said: "We did far more damage to the Labour Party than we did the Conservative Party.
Explaining his reason for refusing to stand next month, Mr Farage, who failed to take South Thanet from the Tories in 2015, said he would be better served travelling the country supporting the party's candidates rather than being "hunkered down" in a single constituency trying to become an MP.
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