These people will be the key players over the next few momentous days as the Prime Minister battles to keep her Brexit agenda, and her premiership, on track.

Theresa May

Theresa May
Prime Minister Theresa May is heading to Europe (Yui Mok/PA)

The PM backed-off from a crunch Commons vote on the EU Withdrawal Agreement in the face of a “significant” defeat.

Mrs May is now set to travel to Europe ahead of a pre-arranged EU summit on Thursday and Friday in a bid to get new reassurances over the backstop arrangements for the Irish border.

The PM’s future hangs in the balance as she faces rising criticism from both pro-and anti-Brexit wings of the Tory party over her handling of EU withdrawal.

Jeremy Corbyn

Jeremy Corbyn
Could Jeremy Corbyn become Prime Minister? (Stefan Rousseau/PA)

The Labour leader is also under pressure from elements of his own party who want him to move a confidence vote against the Government.

Some 50 Labour MPs and peers have urged him to force the issue, as have the Liberal Democrats and SNP.

However, the Labour leadership has made it clear it wants to strike when it considers Mrs May to be at her weakest, and is, for now, keeping its powder dry until it sees what, if anything, the PM brings back from the EU.

Donald Tusk

The European Council president said that Brexit had now been added to the two-day EU summit taking place this week after the events at Westminster.

However, Mr Tusk signalled the EU intends to stand firm, stating that the EU would not renegotiate the deal, or backstop measures on the Irish border issue, but would only discuss “how to facilitate UK ratification”.

Mr Tusk has repeatedly expressed sadness at the prospect of Brexit and its impact on both sides.

Jean-Claude Juncker

Jean-Claude Juncker
Jean-Claude Juncker is backing the Irish government (Matt Cardy/PA)

The European Commission president has also made clear that negotiations will not be re-opened.

Mr Juncker has made a point of saying the EU will stand firm with the Irish government over backstop arrangements for the Irish border which would see the UK remain subject to the bloc’s customs rules if no wider trade deal is agreed before the end of a transition period.

Leo Varadkar

Irish Taoiseach Leo Varadkar (Niall Carson/PA)
Irish Taoiseach Leo Varadkar (Niall Carson/PA)

The Taoiseach has taken a much tougher stance on Brexit issues since taking over as Irish leader from Enda Kenny in 2017.

Heading a minority government and facing possible elections within the next few months, Mr Varadkar cannot afford to  be seen to give ground to the UK at home.

Citing the need to maintain peace in Northern Ireland, Mr Varadkar has insisted that backstop measures must stay in place after the transition period “unless and until” a trade agreement is in place.

Arlene Foster

The DUP leader has been flexing her party’s political muscles over Brexit as Mrs May relies on it for a slender Commons majority.

Mrs Foster has insisted that the backstop measures are unacceptable and the DUP cannot support them.

However, the DUP has said it will back Mrs May if she faces a confidence vote in the Commons, but only if the EU Withdrawal Agreement is voted down or significantly changed.

Angela Merkel

Angela Merkel and Theresa May
Angela Merkel will meet with the PM (Chris Ratcliffe/PA)

The German Chancellor will be a major player in any moves on Brexit.

However, she is now a weakened figure after standing down as the leader of her CDU party, but remaining as Chancellor.

Mrs Merkel will be a key voice in any softening of the EU line, especially as French President Emmanuel Macron is expected to maintain a tough position.

Penny Mordaunt

Penny Mordaunt
Could Penny Mordaunt be the next Cabinet minister to resign? (Victoria Jones/PA)

The International Development Secretary, and prominent Brexiteer has sounded ambivalent about the Brexit deal at times.

At Westminster she is widely seen as the most likely next Cabinet resignation over Brexit.

Other leading Brexiteers, Environment Secretary Michael Gove, and International Trade Secretary Liam Fox, have – so far – publicly backed Mrs May’s stand.

Sir Graham Brady

Sir Graham Brady
How many letters are in Sir Graham’s possession? (Rick Findler/PA)

The chairman of the powerful 1922 Committee of Tory backbenchers is the only person who knows how many MPs have put in letters calling for a vote of confidence in Mrs May.

If the figure reaches 48 Tory MPs then a vote would be automatically triggered.

Sir Graham said he backed the PM’s decision to defer the Brexit vote, but added: “I think it’s best to recognise we are in uncertain times. A very difficult point in British politics.”

Jacob Rees-Mogg

Jacob Rees-Mogg
Jacob Rees-Mogg leads the European Research Group (Victoria Jones/PA)

The arch-Breexiter believes the chances of a no deal exit from the EU have increased due the Prime Minister’s Commons move.

The MP wants a “managed no deal” and has turned up the heat on Mrs May repeatedly insisting a new PM would be needed for such a course of action.

Mr Rees-Mogg was widely considered to have overplayed his hand recently when leading figures from the European Research Group of Tory MPs he heads called for backbenchers to put in letters into the 1922 Committee calling for a vote of confidence in Mrs May.