Theresa May is likely to face a vote of no-confidence in her leadership, a move that could see the British prime minister ousted by her own party over Brexit, according to reports Friday.

Conservative MP and hardline Brexiter Jacob Rees-Mogg publicly called for the vote Thursday, which would need the backing of 48 Conservatives to proceed.

Unconfirmed reports emerged Friday morning that the required 48 letters had been received. The editor of the BrexitCentral news site, citing an anonymous source, claimed that the threshold been reached, while Sky News reported that government whips had been ordered to return to London as a no confidence vote was likely.

When asked Friday morning if the threshold had been reached, Rees-Mogg said: “We’ll see.”

How would it work?

At least 20 Conservative MPs have publicly called for a no-confidence vote, but MPs can also submit letters privately.

Should the vote take place, May will be ousted if a simple majority of her 315 MPs vote for her removal. A leadership contest will then be held to find a replacement. If May survives a vote, her leadership cannot be challenged for at least 12 months.

The ballot will be conducted in secret, with the decision resting with each individual MP on whether to make their vote public or not.

Why do some Tories want her out?

May’s leadership has often looked precarious since she took over from David Cameron in the wake of the EU referendum in June 2016 — particularly after she called a disastrous snap election a year later which slashed her party’s seats in Parliament and left it a minority government.

But this crisis is trumping even that. Her latest troubles began when four ministers resigned Thursday over her draft Brexit agreement with the European Union — including her Brexit Secretary overseeing negotiations.

Will May quit?

Despite the rebellion, May has vowed not to stand down and called for MPs to rally behind her Brexit plan. A key Conservative, Michael Gove, was reported Friday to have decided not to resign, amid widespread speculation he would step aside in what would be another hugely damaging blow to May. Gove had turned down the vacant Brexit Secretary role offered to him Thursday night.

May is pushing to have the draft deal, as agreed with the EU this week, ratified by Parliament before Britain leaves the bloc on March 29, 2019. But the negative reaction to the agreement from across the political spectrum makes it increasingly unlikely May will get the 320 votes needed for the deal to pass, raising the likelihood of a “no-deal Brexit” which many predict will be economically disastrous.

Hardline Brexiters have taken issue, in particular, with a so-called “backstop” approach intended to solve issues on the Irish border. May's plan is for the UK to observe EU customs rules, at least temporarily, until a permanent solution is reached — a situation the Brexiters say is untenable.

Can the Europeans help her out?

Critics say the backlash to May’s draft Brexit agreement has left the deal dead in the water. But while the hardliners are pushing for the government to negotiate a better deal, the Europeans have said there is nothing else on offer.

“We have a document on the table that Britain and the EU 27 have agreed to, so for me there is no question at the moment whether we negotiate further,” German Chancellor Angela Merkel said Thursday night, warning that a “no deal Brexit” come March 29 would be “the worst case, and most disorderly.”