He told the BBC on Saturday that Labour “needs to be better”.
“We’ve got to see this as a moment to reclaim the Labour party, to save it from where it’s been – we can’t just carry on as we are”.
He said that he wanted Labour to “be part of working class people”.
“I think Britain has been on the wrong path for 40 years, it started de-industrialisation, de-regulation of the buses, privatisation of life’s essentials.”
Asked whether the election was a vanity project and voters would be frustrated by another election, he said: “I think this is a very necessary election, it’s about fixing politics because it’s not been working for people.”
Burnham said he would “put everything into it”, adding: “We’re going to change the conversation in this campaign. We’re going to get Labour closer to these communities again.”
The BBC understands the by-election is likely to take place on 18 June.