Theresa May resisted pressure to resign on Wednesday but is widely expected to announce her departure plans on Friday.

The prime minister is ready to tell Sir Graham Brady, chair of the 1922 committee of Tory MPs, that she will leave office on June 10.

The resignation of her Cabinet colleague Andrea Leadsom on Wednesday finally tipped the scales against May.

LONDON — Theresa May is set to resign after losing the support of her Cabinet colleagues.

The embattled prime minister is understood to be preparing to leave Downing Street on June 10, paving the way for a leadership contest. She will meet Sir Graham Brady, chair of the 1922 Committee, on Friday, where she is likely to outline her plan to step aside after a state visit from US President Donald Trump.

The resignation of Andrea Leadsom — the House of Commons leader and May's onetime leadership rival — on Wednesday evening appears finally to have tipped the scales against May, who had already endured a bruising day after a last-ditch attempt to rescue her Brexit plan received a furious backlash.

The prime minister came under intense pressure to resign on Wednesday but resisted calls to do so, in part because voters were participating in the European elections on Thursday.

Friday was the first obvious day to do so, with parliament set to enter recess for nearly two weeks afterwards.

Voting in the European elections will also have finished, meaning May's resignation could not be seen to have had an impact on the Conservative vote share, although the party is already polling on disastrously low figures.

The 1922's committee executive held a secret ballot on Wednesday on whether to rewrite party rules to force another leadership contest if May refuses to quit. The results of the vote have been sealed in an envelope, according to ITV's Daniel Hewitt, which will be opened if the prime minister has not resigned or agreed to resign within weeks by Friday.

What if May doesn't agree to resign?

Theresa May Reuters

If May does refuse to leave on Friday, the 1922 committee plans to change the rules to force another vote of no-confidence in May as Tory leader, which she would lose by a heavy margin.

Current party rules mean the prime minister cannot face a confidence vote in her leadership of the party until December after she survived an attempted coup before Christmas.

However, MPs could change their rules to allow for a vote as early as June.

Even May's allies expect her to announce her departure plan on Friday. One loyal friend of the prime minister told Business Insider that the prime minister would likely quit on Friday rather than face the "humiliation" of MPs forcing her out.

"If she doesn't announce a firm date in the near future she risks the humiliation of the 1922 telling her they are changing the rules and being booted out in a vote of no confidence in a rather undignified way," the MP said.

However, May's resilience has surprised her colleagues before, and it could do so one final time.