Theresa May has challenged Conservative activists to show they have earned the right to form the next government.

The party chairman told grassroots members gathered in Blackpool that they had to provide a credible alternative to Labour."Labour have done enough to lose the next election. Have we done enough to win?" she asked.

"Have we done enough to earn the right to be in government once again?

"Or could Labour win the next election by default?

"Our country cannot afford another five years of Labour government and we are the only party that can put them out of business."

She warned that the party could not rely on being returned to power by its traditional supporters.

Instead, it would have to show it understood "how the people of Britain live today".

And she called on the party's MPs to help deliver victory at the next election.

"If we are going to win, then from every member of the party to every member of parliament, we all must have the will, the drive and the determination to win."

May urged the party to be "united" in showing that "we understand people's lives and share their values and concerns".

She accepted that the party still had "a lot to do".

"But have no doubt, under Iain Duncan Smith's leadership there will be no going back. There is no future in the past," she said.

And May backed an end to "yah-boo" politics in favour of a "different kind of government".

"A government that admits when it's got it wrong. A government that owns up to the fact that it doesn't have all the answers."

The Conservative chairman criticised Labour for thinking that "government alone has the answers to all our problems".

And she added that the Liberal Democrats were best at "being all things to all people all of the time".

May also said that the Conservative Party's organisation would have to be overhauled to face the challenges of the new century.

"That means turning a structure that was designed to support the government of yesterday into a vehicle that can deliver the government of tomorrow."

She said the party was selecting new candidates from a wider range of backgrounds, but the party had to move on to embrace new campaigning techniques.

"It means using email and the internet, using new media, being willing to embrace new ideas and not just relying on our tried and trusted methods or the way we've always done things."