By Andrew MacAskill, Ben Martin and Maiya Keidan

LONDON (Reuters) - Two of the biggest donors to the Brexit campaign say they now believe the project they championed will eventually be abandoned by the government and the United Kingdom will stay in the European Union.

Peter Hargreaves, the billionaire who was the second biggest donor to the 2016 leave campaign, and veteran hedge fund manager Crispin Odey told Reuters they expect Britain to stay in the EU despite their campaign victory in the 2016 referendum.

As a result, Odey, who runs hedge fund Odey Asset Management, said he is now positioning for the pound to strengthen after his flagship fund previously reaped the benefit of betting against UK assets amid wider market fears about the impact of Brexit.

The donors' pessimism comes amid deadlock in Britain's parliament over the exit deal that Prime Minister Theresa May has struck with the EU, which has cast significant uncertainty over how, or even if, Brexit will happen.

Hargreaves, who amassed his fortune from co-founding fund supermarket Hargreaves Lansdown, said the political establishment were determined to scuttle Brexit and this would lead to a generation of distrust of Britain's political classes.

The government, he said, is likely to first ask for an extension to the formal exit process from the EU and then call for a second referendum.

"I have totally given up. I am totally in despair, I don't think Brexit will happen at all," said Hargreaves, 72, who is one of Britain's wealthiest men and donated 3.2 million pounds ($4 million) to the leave campaign. "They (pro-Europeans) are banking on the fact that people are so fed up with it that they will just say 'sod it we will stay'. I do see that attitude. The problem is when something doesn't happen for so long you feel less angry about it."

Turning Brexit upside down would mark one of the most extraordinary reversals in modern British history and the hurdles to another referendum remain high. Both major political parties are committed to leaving the EU in accordance with the 2016 referendum.

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But Odey, who donated more than 870,000 pounds to pro-leave groups, said while he did not believe a second referendum would take place, he did not think Brexit would happen either.

"My view is that it ain’t going to happen," Odey said. "I just can’t see how it happens with that configuration of parliament."

Britain's parliament is viewed as largely pro-European because about three-quarters of lawmakers voted to stay in the EU in the 2016 referendum.

Odey said he had changed his position on sterling over the last month and that the pound "looks like it could be quite strong" and rise to $1.32 or $1.35 against the dollar, from around $1.27 currently.

LEADERSHIP VACUUM

Both Odey and Hargreaves said one reason for their pessimism was a lack of direction from Brexiteers.

"The unfortunate thing is that almost nobody is leading the Brexit charge, so it's leaderless, which is the problem," Odey said.

He said he would be willing to donate to the leave cause in the event of another referendum, while Hargreaves said he was undecided.

Other prominent Brexit supporters who bankrolled the campaign were more optimistic about the project’s fate.

Paul Marshall, chairman of the hedge fund firm Marshall Wace, which runs $39 billion in assets, told Reuters that abandoning Brexit would be wrong and highly damaging.

"Despite the antics in parliament, the prospect of the 2016 referendum being overturned is in my view very small," said Marshall, who gave 100,000 pounds to the leave campaign prior to the vote.

Marshall predicted the most likely outcome is that Britain will leave the EU without a deal in March, or the government will secure a revised Brexit deal, solving the thorny issue of the Northern Irish backstop, which may involve Brexit being briefly delayed.

Another vocal Brexiteer Tim Martin, the chairman of British pub chain JD Wetherspoon, who donated 212,000 pounds to the 2016 campaign, said he was refusing to contemplate a second vote.

He is touring his pubs giving talks to customers about the merits of leaving the EU without a deal and aims to have visited 100 of his sites by the end of January.

A second referendum would be "a nightmare," Martin said.

"It's like saying: 'Do you think we should have another world war?' or 'What do you think about being struck by lightning?'" he said.

(Reporting By Andrew MacAskill, Ben Martin, Maiya Keidan; Editing by Guy Faulconbridge and Janet Lawrence)