Pro-EU campaigners want to team up with Leave supporters to help fund their legal challenge aimed at preventing Theresa May from triggering Brexit without parliamentary approval.
Around 1,400 people have contributed more than £50,000 to the People's Challenge, which means the group has hit the threshold to prepare a written case for the High Court.
Crowd-funding organiser Grahame Pigney, who is seeking to raise a further £100,000 to boost the campaign's legal team in court, insists there is a need to "fight suits with suits" and he is open to Brexit backers joining his cause.
Government lawyers advised in July that the royal prerogative can be used to invoke Article 50 of the Lisbon Treaty - which does not require a vote in Parliament - and reports have suggested May is leaning towards this approach.
Pigney, who represents the Say Yes 2 Europe group, is adamant there must be an Act of Parliament before the Prime Minister triggers the two-year process of negotiating the UK's withdrawal from the EU.
He told the Press Association: "What we're doing is on behalf of everybody - not just experts, not just on behalf of a few people interested in this, but 65million citizens in the UK.
"They all have these rights. Whether they use them or cherish them, they all have these rights and Parliament needs to make the decision rather than the Government in some sectional, political interests.
"I don't see why Leavers can't get behind this as it's about parliamentary sovereignty."
Judges have decided a legal challenge over Brexit can be heard by the High Court in October, with London-based investment manager and philanthropist Gina Miller the lead case in the action.
The legal action has been described as "the most important constitutional law case in living memory", with the People's Challenge aiming to be involved as an interested party.
This could be a source of frustration for Brexit supporters by adding to fears of the UK not triggering Article 50 or using a watered-down approach in negotiations.
Conservative MP Bernard Jenkin, chairman of the Public Administration and Constitutional Affairs Committee, said of the legal challenges: "This is ludicrous, it's desperate and it's people who cannot face the truth that Britain's membership of the European community has lost democratic consent and that's what counts."
UKIP MP Douglas Carswell suggested those pursuing cases against how the EU referendum result is delivered are "out of touch".
He said: "It's very clear as a point of law that the Government can trigger Article 50 without a vote in the Commons.
"The issue is whether or not judicial activists try to subvert the referendum result despite the fact that the law is crystal clear."