British Prime Minister Theresa May held crisis talks with colleagues today in an effort to breathe life into her twice-defeated Brexit deal after reports that her cabinet was plotting to topple her.

A spokesperson for Mrs May said that she held "lengthy talks with senior colleagues about delivering Brexit."

"The meeting discussed a range of issues, including whether there is sufficient support in the Commons to bring back a Meaningful Vote this week," said the spokesperson.

Among the senior members at the meeting was leading Brexiteers Boris Johnson and Jacob Rees Mogg among others.

The United Kingdom's exit from the European Union was already slipping from Mrs May's grasp as she struggles to increase support for her deal and parliament prepares to grab control of Brexit in the coming days.

Nearly three years since the 2016 referendum, it remains unclear how, when or if Brexit will ever take place.

With Mrs May weakened, ministers publicly downplayed any immediate threat to her leadership, insisting that she is still in control and the best option is for parliament to ratify her Brexit divorce deal.

After hundreds of thousands of people marched across central London yesterday to demand another Brexit referendum, Mrs May was the subject of what The Sunday Times said was a "coup" by senior ministers seeking to oust her.

The newspaper cited 11 unidentified senior ministers and said they had agreed that the prime minister should stand down, warning that she has become a toxic and erratic figure whose judgment has "gone haywire".

But two of the leading candidates as caretaker leaders - Mrs May's de facto deputy David Lidington and Environment Secretary Michael Gove - backed Mrs May today.

Mr Hammond said the best way forward would be for parliament to back May's deal, and if MPs did not, they should then try to find a way to end the deadlock.

"I'm realistic that we may not be able to get a majority for the prime minister's (Brexit) deal and if that is the case then parliament will have to decide not just what it's against but what it is for," he said.

Brexit had been due to happen on 29 March before Mrs May secured a delay in talks with the EU on Thursday.

Now a departure date of 22 May will apply if parliament rallies behind the prime minister and she is able to pass her deal. If she fails, Britain will have until 12 April to offer a new plan or decide to leave the EU without a treaty.

Some politicians have asked Mrs May to name her departure date as the price for supporting her deal, though it was unclear when a third vote might take place.

If May's deal is dead, then parliament will try to find a different option. That opens an array of possibilities including a much softer divorce than Mrs May had intended, a second referendum, a revocation of the Article 50 divorce papers or even an election.

MPs are due to debate a government motion tomorrow saying parliament has considered a statement made by Mrs May on 15 March setting out the government's next steps on Brexit, including the plan to seek a delay.

They are likely to propose changes, or amendments, to this motion setting out alternative ways forward on Brexit. These are expected to include a proposal to approve Mrs May's deal only if it is put to a public vote.

While amendments are not legally binding, instead simply exerting political pressure on Mrs May to change course, MPs could use one to seek change in parliamentary rules to wrest control of the Brexit process from the government.