Tony Blair has vowed to ride out his "rough patch" and told delegates at Labour's annual conference that he has "not got a reverse gear".
Tony and Cherie Blair before the speech
In what was trailed as one of the most important speeches of his leadership, Mr Blair gave a resolute defence of his decision to invade Iraq - and said he was ready to meet the challenge of winning an historic third term in government.
The prime minister received a standing ovation before and after the speech despite many delegates being unhappy with his policies on foundation hospitals, tuition fees and the war.
Delegates will be now able to debate and vote on Iraq on Wednesday, after the committee thrashed out a deal for a 75-minute discussion.
In his speech Mr Blair urged activists to keep faith with him and - in an effort to quell criticism that policy is foisted on the party without consultation - promised the biggest policy consultation ever seen in Britain.
The British public would not forgive cowardice in the face of a challenge, argued Mr Blair, whose speech was delayed after a man apparently tried to perform a citizen's arrest on him as he arrived at the conference hall.
"I can only go one way, I've not got a reverse gear."
Pointing to his "testing times", Mr Blair said: "Government is tough. Fulfilling, but tough."
He said he was surprised it had taken so long for things to become difficult - but in a signal of his intent to ride out his troubles, he said: "What to do... give up on it - or get on with it?"
He pointed to Labour's "spasmodic" periods in power and said for most of its 100-year history it had been a "well-intentioned pressure group" frequently defeating itself once in government.
In a recognition of the challenge he has in rebuilding trust, Mr Blair said: "I know it's hard for people to keep faith, some of the
people may have a different take on me. But I have the same take on them.
"I trust their decency, I trust their innate good sense."
On the key issue of Iraq, Mr Blair said he respected his critics, but: "I ask just one thing: Attack my decision but at least understand why I took
it and why I would take the same decision again.
"Imagine you are PM, and you receive this intelligence and not just about Iraq but about the whole murky trade in WMD... So what do I do?
"Say 'I've got the intelligence but I've a hunch it's wrong'?"
Whatever the disagreements, people should recognise at least that Iraq was a better place without Saddam Hussein, he argued.
'Fairness in choice'
Mr Blair said that it would be "madness" to give up on the UK's option of joining the euro.
And there was a spirited defence of controversial attempts to reform public services, such as the foundation hospitals scheme and student tuition fees.
In a rare use of the word "socialism", he said he wanted the middle classes to be fighting to get into the state sector, but on the same basis as everybody else.
"Choice has always been there for the well-off... What is unfair is not the right to choose, not the pursuit of excellence, but where that choice depends on your wealth not on your need."
He was "restless" about how much there was still to do, he said, explaining why he "banged the drum for change".
Labour should not just aim for a third term in power but also for a "historic alignment of the political forces shaping our country and the wider world", he said.
The speech comes a day after Chancellor Gordon Brown made an impassioned plea to party members not to let tough times deflect them from the "often hard... Labour road" to transform society.
While it was not obvious that Mr Brown had said anything overtly critical of the prime minister, observers instantly saw it as the chancellor setting out his leadership stall.
It also follows Education Secretary Charles Clarke's address to delegates on issues including the government's controversial plan for university funding.
GMB leader Kevin Curran branded Mr Blair's speech a "missed opportunity", arguing that warning of the dangers of "right-wing Tories" was not enough.
But Unison general secretary Dave Prentis said: "This is the speech of a
conviction politician at his best... but the real test will be whether he is
willing not just to listen but to respond to the people's concerns."
Former Labour leader Neil Kinnock said Mr Blair had earned respect by being honest about the dilemmas facing him, especially over Iraq.
But the Conservatives said his "no reverse message" contrasted to his chancellor's back to old Labour approach.