James Cleverly will tell the Tories on Tuesday that they must promise to “build, build, build” if the party is to find a way back to power.

In a speech to the Conservative conference, the former home secretary will argue that the party has to be “for” things again, rather than always appearing to be against change.

He will argue that the Tories need to remake the argument for conservatism and capitalism, support people to build a family, and build more homes.

They must also cut red tape to enable Britain to build vital infrastructure to inculcate a “new generation of optimism in the tradition of Macmillan and Thatcher”.

The policy on housing could prove a dividing line with other leadership candidates, who may accuse him of putting the green belt at risk.

Labour has pledged to “bulldoze” the planning system and build 1.5 million homes in five years to enable younger people to get a foot on the housing ladder.

While Mr Cleverly will not get into figures, he will argue that a promise to “build, build, build” is necessary to overturn the view that the Tories are the “grumpy” party for always opposing things.

He will say: “How do we face up to the great challenges of our time? How we have always done it. Be for stuff again. British science and engineering shaped the modern world.

“We are the country that gave the world the vaccine (twice), the steam engine, the light bulb, the World Wide Web, the bicycle, the tank, the people that split the atom.

“We need more ‘yes we can’, both from our party and our country.

“Remake the argument for conservatism and capitalism by our actions, not just our words.

“Build more homes so we can build a new generation of optimism in the tradition of Macmillan and Thatcher.

“Cut the cost of childcare, so people can afford to build a family. Cut red tape so we can build the energy and transport infrastructure we need more cheaply.

“Build, build, build.”

He will add: “And let’s get rid of bad taxes like stamp duty. Make sure that work always pays – and the state never takes more than half your earnings.

“And be the party of free markets and freedom. Of business and entrepreneurs. Get on their side, and out of their way. These are my values.”

On Monday, Tom Tugendhat, his leadership rival, said he was a believer in “building the right things in the right places” when asked about planning.

Asked if he was a “yimby”, a “nimby” or a “banana” (build absolutely nothing anywhere near anything), the former security minister was cheered when he said: “It sounds disgusting and yellow, so it must be Lib Dem.”

Kemi Badenoch suggested on Monday that she would like to see more housing built to make it easier for people to start a family.

She told an event with the Conservative Women’s Organisation that a shortage of housing could be affecting the birth rate.

“I think that there are things that we have to do to make sure that we make life comfortable for those people who are… starting families,” she said, listing examples such as maternity pay, childcare provision and housing.

“A lot of people have fewer children because they start having children later,” she said.

‘Covid-19 lockdowns were wrong’

Speaking at the conference on Monday, Mr Cleverly said the worst thing about 14 years of Tory government was the response to the Covid-19 pandemic – but he would not commit to never supporting a lockdown again.

“The lockdowns were wrong. We got it badly, badly, badly wrong,” he said.

“We cancelled Christmas. We became fearful and as a society, introspective, and it brought out all the worst.”

When asked if that meant he would never support another lockdown, he said: “Well look, you can’t say that, because if something like the bubonic plague was coming out… what we know now, which we didn’t know at the time, was the risk profile of Covid-19.”

The former home secretary also said children should not be allowed to “dictate” their gender identity to adults.

“I clearly missed the memo when we collectively decided that children dictate to adults and adults don’t teach children, because that strikes me as a bit of a recipe for disaster,” he said.

“We know, and this is not a criticism, it is just a statement of biological fact, human children are born with not fully developed brains.

“It is how we get an animal with a very large skull through the pelvic bone of a woman.”

Mr Cleverly also urged the Tories to stop “behaving like bloody children”.

“The first thing we need to do is win back the trust and support of the voters,” he said. “We behaved appallingly.”

Asked how the party could do this, he replied: “Um, stop behaving like bloody children.”