Media playback is unsupported on your device Media caption Ed Miliband: "I will put up with whatever is thrown at me in order to fight for you"

Labour leader Ed Miliband has pledged to take on "vested interests" and "powerful forces" in his bid to win the next general election.

In a speech at the University of London, he said he would tackle a "zero-zero economy", saying people were on so-called zero-hours contracts while the rich "get away with zero tax".

It comes amid reports some Labour figures want him to step down.

He said he would "put up with whatever is thrown at me".

With his personal poll ratings lagging his rivals, Mr Miliband said it was the party's "duty... not to shrink from the fight, not to buckle under the pressure but to win".

There is a saying 'what doesn't kill you makes you stronger'. Being Leader of the Opposition, particularly in the last few days, I know what it means. Ed Miliband EPC

Watch key moments from the speech

He said anyone who thought his job was hard should think about people doing "really hard jobs" like shift work, night work and having multiple jobs.

Labour would be "talking more about immigration as a party", he said, "but always on the basis of Labour values, not UKIP values".

In a direct attack on Mr Farage's party, he said UKIP had "got away with it for too long", listing what he said were the party's policies on the NHS, gay marriage and single mothers.

Media playback is unsupported on your device Media caption Ed Miliband tells Nick Robinson he has not thought of quitting

It was natural to feel a sense of longing for the past, he said, but added: "Mr Farage, you may want to live in that world but come the general election, I don't believe the British people will follow."

Mr Miliband said Labour would not try to "out-UKIP UKIP", but called for a debate on where the party stood.

Mr Farage responded with an open letter challenging Mr Miliband to a live, televised debate ahead of the general election.

Facing questions after his speech, Mr Miliband was asked what the vested interests were, and pointed to banks and energy companies.

'Deeply sceptical'

He said: "I do not think any forces should be too powerful, and I actually think that's what the British people are thinking."

Asked about economic growth and wages overtaking inflation for the first time in five years, Mr Miliband said: "The Tory view is that the economy is fixed."

Image copyright PA

Image copyright PA

Image copyright PA

He said: "What I think people feel is that this is a country works for a few people at the top, but the recovery is not reaching me and my family."

In an interview with BBC political editor Nick Robinson ahead of the speech, the Labour leader admitted his "mettle had been tested" by reports that some Labour figures thought he should step down.

But he denied his leadership was a problem and said: "What doesn't kill you makes you stronger."

Asked why the Labour Party was struggling, Mr Miliband said many people were "deeply sceptical about mainstream politics and whether it can solve their problems".

'Learn lessons'

Shadow health secretary Andy Burnham said there had not been a "shred of truth" in a newspaper story linking him with a leadership plot, calling it "pure fiction".

Speaking on BBC Radio 4's Today programme, he said Mr Miliband had shown "courageous leadership" in the face of attacks from "vested interests" who did not want Labour to win.

He added: "There has been a campaign in the last few days to destabilise and demoralise us.

"My message today is that it won't work, in fact it is going to galvanise us."

Media playback is unsupported on your device Media caption Andy Burnham MP: "Ed Miliband is fully in control"

Conservative chairman Grant Shapps said of the Labour leader: "Ed Miliband's tenth relaunch does not cover up his failure to learn the lessons from Labour's mistakes.

"He has opposed everything we've done to turn our country around; he's failed to put forward an economic plan to secure Britain's future.

"Voters will view this latest effort with the same lack of enthusiasm that Ed Miliband's own colleagues view his leadership."

Speaking on his LBC radio phone-in, Lib Dem leader Nick Clegg said Mr Miliband's "greatest failure" was "that he doesn't acknowledge Labour's responsibility for the monumental economic crash they helped create the conditions for in the first place in 2008".