LONDON (Reuters) – Prime Minister Theresa May faced a backlash on Wednesday from prominent supporters of Brexit after reports that she is ready to pay much of what the European Union is demanding to settle the country’s “divorce bill” to leave the bloc.

The Daily Telegraph newspaper said the net bill would total 45 billion to 55 billion pounds. A government official cast doubt on those numbers and the European Commission declined to comment, but there is a growing expectation that the sides will clinch a deal on cash.

Veteran Brexit campaigner Nigel Farage told Reuters Britain should walk away from the talks rather than offer such huge sums.

“This is a complete sell-out that is not in our national interest,” said Farage, a former leader of the UK Independence Party (UKIP) who played a big role in the 2016 referendum in which 52 percent of Britons voted to leave the EU.

“The British prime minister needs to say: ‘Look, either start to behave reasonably, either start to behave in a grown-up way, or … we are walking away’,” said Farage, who remains a member of the European Parliament.

Many businesses and investors fear such an approach, leading to a “disorderly Brexit”, would spook financial markets, sow legal chaos and badly harm the British and EU economies by disrupting trade ties and cross-border supply chains.

Farage and pro-Brexit entrepreneurs such as billionaire Peter Hargreaves say Britain can prosper outside the EU and what they see as its onerous rules and regulations.

Britain, which is due to leave in March 2019, hopes to persuade EU leaders next month that the sides have made enough progress on three key issues – the rights of EU citizens living in the UK, the exit bill and the land border with Ireland – to be able to move on to talks on a post-Brexit trade relationship.

“THANK YOU AND GOODBYE”

Brexit supporters in May’s ruling Conservative Party also expressed concern about the possible size of any financial settlement during a debate in parliament on Wednesday.

Jacob Rees-Mogg, a prominent Conservative lawmaker, said Britain seemed to be “dancing to the tune” of the EU and sought assurances that no payments would be made unless there was a full agreement on trade.

Echoing that comment, Conservative lawmaker Philip Davies said “any spare money” should stay in Britain at a time of austerity, not “given in a bung to the European Union”.

In contrast, Foreign Secretary Boris Johnson, one of the leaders of the 2016 ‘Leave’ campaign, signalled flexibility on the cash issue, saying it was “time to get the ship (of negotiations) off the rocks”.

However Hargreaves, the second biggest donor to the Leave campaign, denounced the government’s handling of Brexit talks, saying they showed no understanding of the sums involved.

“We ought to say to the EU: ‘Thank you very much, we are never going to get a deal, goodbye’ and we are gone, lock stock and barrel, and carry on trading as before,” Hargreaves said.

Farage dismissed calls by some opponents of Brexit such as former prime minister Tony Blair that British voters might change their mind about leaving the EU.

“The revolution of 2016 is still rolling,” he said. “The European Union project is in deep trouble and it’s only a matter of time until it ends.”

The EU’s supporters say it has helped to cement peace and prosperity in a continent historically ravaged by wars.

Farage’s foes see him and his party – now riven by divisions and with no lawmakers in the UK parliament – as dangerous populists who misled voters on the true costs of Brexit.

It was fear of losing support to Farage’s UKIP that helped persuade May’s predecessor as Conservative prime minister, David Cameron, to hold the 2016 referendum. Both Cameron, who resigned immediately after the vote, and May voted to stay in the EU.