Tories are "dying out" and need a partnership with far-right Ukip to prop up an all-time low in party membership, according to a senior Conservative think tank.

The Bow Group says the desperate Tories need to return to the grassroots by forging an electoral pact with Ukip - a party which has been accused of stoking racism and xenophobia with its anti-immigrant policies.

A BBC poll suggests that a quarter of Tory councillors agree with the proposals, while a number of high-profile Conservatives have also floated the possibility of an alliance with Ukip to avoid splitting the right-wing vote.

On the opening day of the Conservative conference,  Bow Group chairman Ben Harris Quinney said the proposed move is needed to resuscitate membership, which has halved since David Cameron came into power.

He said: "The nature of the modern Conservative Party conference reflects its crisis in willing support. Conference is now populated by lobbyists, not members.

"It offers no freedom and no democratic rights to a membership who barely recognise or connect with what the party has now become."

The think tank believes that tapping into Ukip's populist base is the key to regaining members.

The Conservative Party has 134,000 in its ranks and is on course to have fewer members than Ukip in five years, it says.

Ukip, which has attracted right-wing voters despairing of Conservative policies on gay marriage, foreign aid and Europe, has swollen to 30,780 today from 15,535 in 2010.

The plan comes after news that Ukip leader Nigel Farage was labelled a racist by his schoolteachers, who said he used to sing Hitler Youth songs as a teenager at exclusive public school Dulwich College.

Thurrock Ukip councillor Robert Ray has also been exposed as a former National Front member.

At the party conference, Foreign Secretary William Hague said Tories "don't make pacts with other parties" despite the poll suggesting 22 per cent of Tory councillors think it's a good idea.

But Tory candidate Toby Young said enacting the proposal was a bottom-up procedure and did not need a green light from the leadership.

He said: "The most common objection to a Con-Ukip pact is that neither David Cameron nor Nigel Farage will touch it, but a pact doesn't need to be endorsed by the leaders of either party to work."