LONDON, July 9 (Xinhua) -- British Prime Minister Theresa May on Monday night vowed to fight any challenge to her leadership after a day of high drama at Westminster.

First her chief Brexit minister David Davis resigned from her cabinet, followed hours later by the resignation of one of her top ministers, the Foreign Secretary Boris Johnson.

It prompted May to carry out a mini-reshuffle of her top team in the cabinet.

RESIGNATIONS OVER SOFT BREXIT

The two resigned over May's proposals for a soft Brexit, which Davis said did not deliver what people voted for in the 2016 national referendum when the majority of people in Britain opted to leave the European Union (EU).

Johnson, in his resignation letter to 10 Downing Street, told May that Brexit should be about opportunity and hope, adding "that dream is dying, suffocated by needless self-doubt".

Reminding May what he said at her awayday meeting last week, Johnson said: "I said then, the government now has a song to sing. The trouble is that I have practiced the words over the weekend and find that they stick in the throat. We must have collective responsibility. Since I cannot in all conscience champion these proposals, I have sadly concluded that I must go."

Addressing MPs in a rowdy House of Commons chamber, May disputed what Johnson had said and insisted that her proposals were in keeping with what the British electorate had voted for, saying she rejected the views of the deal by both resigning ministers.

May said Brexit negotiations with the EU have settled virtually all of the withdrawal agreement, but the two models on offer from Brussels were not acceptable.

She told MPs: "A responsible government must prepare for a range of potential outcomes, including the possibility of no deal, and given the short period remaining before the conclusion of negotiations, the Cabinet agreed on Friday that these preparations should be stepped up."

"It is the Brexit that will deliver on the democratic decision of the British people, and it is the right Brexit deal for Britain," she said.

MIXED REACTIONS

Jeremy Corbyn, leader of the main opposition Labour Party, told May that if her government could not get its act together it should make way for those who can.

Corbyn told MPs: "It is two years since the referendum and 16 months since article 50 was triggered, and it was only this weekend that the members of the cabinet managed to agree a negotiating position among themselves -- and that illusion lasted 48 hours."

"We have a crisis in the government: two Secretaries of State have resigned, and we are still no clearer about what our future relationship with our nearest neighbors and biggest trading partners will look like," Corbyn said.

Saying the Chequers compromise took two years to reach and just two days to unravel, Corbyn added: "How can anyone have faith in the Prime Minister getting a good deal with 27 European Union Governments when she cannot even broker a deal within her own Cabinet?"

Gina Miller, who took the British Government to court in her battle to secure a parliamentary vote on a Brexit deal, described the day's events as extraordinary.

She said: "It's open warfare within a political party that is not putting the country first or second or third. What all of us should be calling for: stop fighting and blackmailing each other; put together a plan, with details not just dogma, then put it to the EU -- get the best deal you can; then put it to the people to validate."

Miller said the question should then be to leave or not to leave the EU, adding. "This is hugely damaging to our national interest and global reputation."

David Blake, professor of finance at the Cass Business School in London said: "When two cabinet ministers resign on the same day, we should sit up and ask whether a sense of reality is beginning to return to the 'Alice in Wonderland' world that Brexit has become."

Blake added: "There are only two coherent cases: being fully in the EU or fully leaving. There is no coherent half-way house."

Later this week the British government will publish full details of the Brexit deal it wants with Brussels. It will then become clear how EU negotiators react to her plans.

NO-CONFIDENCE VOTE

Downing Street insisted that May would fight to keep her job if Conservative MPs triggered a no-confidence vote in her.

Conservative rules mean that 15 percent of the party's MPs would have to back a call for a confidence vote, meaning 48 politicians would have to write to Sir Graham Brady, the chairman of the 1922 committee, to trigger the process.

Political commentators were posing the question Monday night whether two of her biggest ministers quitting would badly wound May's government, and whether the changes so close to negotiations with Brussels reaching a critical stage, could wreck Brexit altogether.

Professor Jon Tonge from the University of Liverpool told Xinhua that the resignations of Davis and Johnson could actually strengthen May's weak hand towards a slightly softer Brexit.

Tonge, an expert in British and Irish politics, said a snap general election was possible, but he thought it unlikely following the result of the election May called in 2017 which led to her losing her narrow majority in the House of Commons.

He added that a confidence vote was very likely, predicting that May would probably win such a challenge among her Conservative MPs.