The Labour Party conference begins under the leadership of Ed Miliband after he dramatically won the top job by a wafer-thin majority over his brother David.
As activists arrive in Manchester for the annual gathering, the new Opposition leader will set out his vision for taking on the Tory-Lib Dem Government.
He wasted no time in attacking the Government, pledging at his first party event last night to work "every hour of every day" to remove David Cameron from Downing Street.
And as the Tories quickly seized on his reliance on trade union votes to secure the leadership as evidence of a shift to the left, he used a newspaper article to say he was "on the side of the squeezed middle".
He conceded that Labour had "a lot of ground to make up" and faced a "long journey" to get back into government but said he approached the challenge with "relish".
He said he would ensure the party recognised its mistakes - over issues such as housing, immigration, student fees and the Iraq war, acted as a responsible opposition and presented a "constructive" alternative.
"We need to accept the mistakes we made in these areas and show that we have changed. We must never again lose touch with the mainstream of our country," he said.
Labour would "not oppose every cut" to be put forward in the Coalition's radical deficit reduction plans next month, recognising that in some areas "public services will now need to learn to do more with less", he said.