They will target key parts of towns and cities up and down the country, including Stoke, Dudley, Carlisle and the Don Valley.
A leaked document shows that activists have been given a briefing pack on how to deal with key issues that “may come up on the door” alongside advice to lobby their neighbours as well as family members, friends and work colleagues.
The aim is to build a “groundswell” of opposition to Brexit.
As well as knocking on doors, the campaign group Best for Britain wants to canvass thousands of voters over the telephone by encouraging volunteers to set up “phone banks” across the country.
Activists have also been told to flood their MPs with a flurry of phone calls co-ordinated on the same afternoon to put them under pressure to support another referendum on the final Brussels deal.
Best for Britain, which is backed by billionaire financier George Soros, plans to spend £5.6million to try to halt the UK’s exit.
John Longworth, co-chairman of pro-Brexit campaign group Leave Means Leave, said: “Best for Britain are an anti-democracy movement bankrolled by George Soros.
“They are insulting British voters and our proud British democracy. It is absolutely shameful that they continue to work against the best interests of Britain.”
Critics also likened the organisation to religious groups looking for converts.
Tory MP Andrew Bridgen said: “They are going door to door like zealots trying to convert people to a discredited belief system, a bunch of Remainer Witnesses.”
Eloise Todd, chief executive “Our mission is to train and allow people to lobby their friends, neighbours and colleagues who together can lobby MPs. When people hear from this groundswell we think, we can stop Brexit.”
Campaigners have also been given advice on how to have what is described as a “conversation funnel” on issues like immigration.
They have been told to play on people’s feelings including that the “emotional argument” made by some Leavers is that immigrants are taking jobs.
They are advised to turn the conversation to the idea jobs is the “real issue” and tell those who back Brexit “I’m sure nobody voted to be worse off”.
Business leaders predict rosy summer
Business leaders today hail growth in the UK economy in the past three months.
The CBI said that falling inflation and rising wages meant the forecast for the summer was equally rosy.
“Growth is tipped to pick up further next quarter,” said spokeswoman Anna Leach.
“With inflation coming down and wage growth edging up, the squeeze on household incomes is set to ease in the coming months,” she added.
However, she said business rates were still a drag on the high street.
Bank of England governor Mike Carney also admitted recently that business rates had become a “real issue” across the country.
The Sunday Express revealed earlier this year that three shops closed on the high street every day last year amid soaring business rates.
The CBI went on to say manufacturers would continue to benefit from sterling rates and solid global economic growth.
The business organisation blamed the winter’s cold weather for slow economic growth in the first quarter of this year.