Rebecca Long-Bailey has called for workers to be given the right to ignore work emails and messages outside working hours to end the “24/7 work culture” and protect mental health.

The Labour leadership candidate said she would bring new ideas to the party, having worked on her policy positions for four years.

Speaking to BBC Breakfast, Long-Bailey, the MP for Salford and Eccles, defended the manifesto Labour fought on in December’s election, saying it contained “some of the most transformative policies in a generation”. However, she lamented that many of the policies were not explained properly.

“We didn’t have a message which spoke to our communities,” she said. “We need a focused manifesto for the next general election.”

Asked where mistakes had been made in the manifesto, Long-Bailey said it was not clear enough which policies were short-term, and which – such as the four-day week – would be implemented over a longer term.

“There were elements in the manifesto that were deliverable in five years, [but] there were also elements in the manifesto that were a longer-term plan,” she said. “So, for example, the four-day working week was one of them. That is a long-term aspiration that would have happened after we’d improved productivity with a robust industrial strategy, when we’d improved trade union rights to make sure people could collectively bargain for that. But many of our voters thought that was going to happen straight away on day one, and it wasn’t.”

Asked if there was enough time for Labour to recover from its heaviest election defeat since 1935, Long-Bailey said: “We have to do it quickly enough.”

Questioned on where Labour had gone wrong in the last election, she said there had been poor messaging and too many policy positions emerging too quickly. “We were announcing policies every day, even [I] found it difficult to keep up.” She added that she had lobbied hard for the green industrial revolution pledge to be put front and centre of the campaign but “unfortunately” that had not happened.

Long-Bailey said she was in the Labour leadership race to win, but she would work with whoever became the next leader, saying that she liked all the candidates. “I want to win,” she said. “We’ve got nine weeks to go and a lot will happen and it will hopefully become a battle of ideas.”

Long-Bailey is one of the frontrunners in the Labour leadership contest, in which she has been characterised as the leftwing heir to Jeremy Corbyn, standing against Keir Starmer, Lisa Nandy and Emily Thornberry. The result will be announced on 4 April.