Heidi Allen and Sarah Wollaston, two of the party's most vocal opponents of Brexit, are believed to be ready to resign imminently despite friends pleading with them to stay, sources closes to both have told Business Insider.
Their backbench colleague, Anna Soubry MP, is on a "knife-edge" and considering breaking away, the same sources said.
BBC Newsnight reports that the three aforementioned MPs are expected to quit the Conservatives tomorrow and join the "Independent Group" of eight former-Labour MPs.
Allen, Wollaston and Soubry are leading supporters of the People's Vote campaign for another Brexit referendum and have implored the prime minister to pursue a softer break from the European Union at the very least.
However, May's refusal to adopt these positions plus a widely-shared belief that they will soon be ousted by an increasingly hardline, pro-Brexit party membership, has led them to the brink of walking away for good.
An ally of Allen told BI that they had emailed her this week, "begging her to stay" in the party.
Figures in the "moderate" wing of the Tory Party are furious with Conservative Campaign Headquarters for failing to prevent former UK Independence Party supporters and hardline Brexiteers flooding local parties nationwide.
Allen, Wollaston and Soubry plus other Conservative MPs are being threatened with deselection by party members.
One Conservative source told BI this week: "If the party doesnt act soon enough were going to experience a wave of deselections as more and more moderate MPs get targeted.
"We want and need these people to make sure we win a majority next time round. United we form a paradoxical grouping occasionally but one which properly represents the diversity of thought in the country.
They added: "Whatever the outcome the likes of Leave.EU wont ever be happy Margot James and Tobias Ellwood both voted for the prime minister's deal and theyre still being targeted for Gods sake."
This follows a warning from the party's former leader and ex-prime minister, Sir John Major, that the party's membership was dragging it further to the right of the political spectrum.
The party membership "appears to be 'hollowing out' traditional Conservatives, while former UKIP members strengthen the anti-European Right of the party," Major warned in a speech on Tuesday.
Former Cabinet minister Justine Greening, another MP who has been linked to a potential Conservative split, has reassured allies this week that she intends to stay in the party.
However, least a small handful of Tory MPs are expected resign and become independent MPs, joining eight MPs who abandoned the Labour Party to form "The Independent Group" this week.
The former Labour MPs cited party leader Jeremy Corbyn's handling of Brexit and allegations of antisemitism within his party as the main reasons for their decision to quit after months of tension and speculation.
SEE ALSO: More Labour MPs are set to quit the party as Corbyn refuses to back a new Brexit referendum
