Factbox - What do British politicians say about another referendum on Brexit?

LONDON (Reuters) - The crisis in Prime Minister Theresa May's government over her plans to leave the European Union has stirred interest in the possibility that Britain may hold a second vote on whether to end decades of membership of the world's largest trading bloc.

A few months ago, such an idea looked inconceivable. But the idea is now being widely debated.

May last week survived the gravest threat yet to her embattled leadership, winning a party confidence vote, but this does little to improve her chances of getting her Brexit deal through Parliament.

As May's political options narrow, the idea of throwing the question back to the public is gaining momentum.

Below is what key politicians say about holding another vote:

Prime Minister Theresa May:

"Let us not break faith with the British people by trying to stage another referendum.

"Another vote which would do irreparable damage to the integrity our politics, because it would say to millions who trusted in democracy, that our democracy does not deliver."

Opposition Labour Party leader Jeremy Corbyn:

"It's an option for the future, but not an option for today. Because if you have a referendum tomorrow, what is the question going to be on, what’s the question going to be?"

Former Prime Minister Tony Blair:

"What seemed a few months ago unlikely is now I would say above a 50 percent likelihood. We will go back to the people. Ultimately, this could even make sense to the PM, who could perfectly legitimately say, 'I did my best, my deal was rejected by parliament.

"In a new referendum both sides will be able to make their case in the context of the experience of the Brexit negotiation, and what we have learned through it."

Former Prime Minister John Major:

"It has downsides. I mean, frankly, a second vote has democratic downsides. It has difficulties. But is it morally justified? I think it is,

"If you look back at the Leave campaign, a great many of the promises they made were fantasy promises. We now know they are not going to be met."

Nigel Farage, the former U.K. Independence Party leader and a leading proponent of Brexit, said:

"My message, folks, tonight is, as much as I don’t want a second referendum, it would be wrong of us......not to get ready, not to be prepared for a worst-case scenario

"Can I urge you, can I implore you to get ready for every situation? I think they will, in the next few months, betray us completely and let us be ready not just to fight back, but if it comes, we will win it next time by a much bigger margin."

Liam Fox, Britain's trade minister and a supporter of leaving the EU:

"Supposing we had another referendum. Supposing the remain side won it by 52 to 48 but it was on a lower turnout, entirely possible

"Let me tell you that if there is another referendum, which I don’t think there will be, people like me will be immediately demanding it is best of three. Where does that end up?"

Boris Johnson, the former foreign minister:

"They (the public) would know immediately that they were being asked to vote again simply because they had failed to give the 'right' answer last time. They would suspect, with good grounds, that it was all a gigantic plot, engineered by politicians, to overturn their verdict. A second referendum would provoke instant, deep and ineradicable feelings of betrayal.

(Reporting By Andrew MacAskill; editing by Guy Faulconbridge)