Ed Miliband has branded the coalition "a bad Government that is letting down the good people of this country", in a New Year's message promising that Labour will offer Britain hope in 2013.
Mr Miliband acknowledged that there were "no easy answers" to the country's problems, but insisted: "I do believe that Britain can be better than it is. There can be hope for people again."
He promised to flesh out his One Nation Labour slogan in the new year with concrete policies on business, education and welfare.
Labour's approach will be based on the principle that "we cannot write anybody off in our country", and will challenge the idea that wealth "trickles down" from those at the top of the economy, he said.
Instead, policies should aim to reward "the forgotten wealth-creators of our country", such as people doing two jobs to make ends meet, small businesses struggling against the odds and young people seeking qualifications and work.
But he also warned that a One Nation society will require "responsibility" at every level of society, from corporations paying their fair share of tax to Government helping ensure jobs are available and those who are able to work taking on employment when it is offered.
In a notably positive message, Mr Miliband said that Britain must harness the Olympic spirit of 2012 as it faces the future. And he hailed the "indomitable spirit" of people trying to find work in the current difficult economic conditions, including a man he met at a food bank who had walked 11 miles to a job interview because he could not afford the bus ticket.
In what is likely to be seen as a swipe at David Cameron, the Labour leader said: "We've all at least got to imagine walking in the shoes of others, to be the man who walked 11 miles to the job interview. That's what it means to be a One Nation Prime Minister."
Mr Miliband sought to use the video address to draw a contrast between a "government of broken promises and broken dreams" and a Labour opposition offering hope for the future.
Without giving any details about new policy proposals, Mr Miliband said he aimed to "tip the scales towards hope" and ensure that Britain uses the talents of all of its people.