Former chancellor George Osborne says there is an "enormous gap" in the centre ground of UK politics.
He said "hard Brexiteers" had dragged the Conservatives to the right, while Jeremy Corbyn had moved Labour left.
"I don't believe that the moderate, pro-business, socially liberal, internationalist part of the British people has disappeared," he said.
He spoke alongside former prime minister Tony Blair who warned of politics based on "shouting loudest".
The two former political opponents, speaking together at an international education conference, warned of a polarised political culture.
'Re-thinking' the centre
The centre ground was where general elections used to be fought and won, Mr Osborne told the Global Education and Skills Forum in Dubai.
The middle ground might have been eroded by the financial crisis and by divisions over Brexit said Mr Osborne. But he argued that it was where many voters still remained.
The former chancellor said that Labour would be far ahead in the polls with a more moderate leader.
Mr Blair said the culture of "building bridges" in politics seemed to have been lost.
Instead he warned that party politics reflected the type of polarisation and taking of extreme views found on social media.
"Those of use in the centre are going to have to do a lot of re-thinking," said the former Labour leader.
'Eccentric' White House
On threats from Russia and the rising economic power of China, Mr Blair warned that "liberal democracy" would face growing challenges.
He called for the US to be much clearer in its defence of western democratic "values".
But Mr Osborne said that unity between Western allies had become much more difficult under an "eccentric" and "unpredictable" Trump administration, with a high turnover of senior staff.
"It is very difficult for America's allies," said Mr Osborne.
On the diplomatic row with Russia following the nerve agent attack in Salisbury, the former Conservative chancellor said it was important to send out a "tough response".
But he labelled as "disgraceful" the way that the Labour leader appeared to distance himself from the government's claims over Russian involvement.
Mr Osborne also revealed another connection with Mr Blair.
He said during Mr Blair's time in Downing Street, Mr Osborne used to rehearse Conservative leaders getting ready to face prime ministers' questions in the House of Commons – and in those exchanges Mr Osborne played the part of Mr Blair.