The hour-long speech in Liverpool came against a backdrop of Sir Keir’s plummeting personal approval ratings and a trade union revolt over winter fuel payment cuts.
He said: “I understand many of the decisions we must take will be unpopular. If they were popular, they’d be easy.”
The Prime Minister said “the time is long overdue for politicians to level with you about the trade-offs this country faces”, listing some of those.
“If we want justice to be served some communities must live close to new prisons,” he said. “If we want to maintain support for the welfare state, then we will legislate to stop benefit fraud. Do everything we can to tackle worklessness.
“If we want cheaper electricity, we need new pylons overground, otherwise the burden on taxpayers is too much.
“If we want home ownership to be a credible aspiration for our children, then every community has a duty to contribute to that purpose.
“If we want to tackle illegal migration seriously, we can’t pretend there’s a magical process that allows you to return people here unlawfully without accepting that process will also grant some people asylum.
“If we want to be serious about levelling up, then we must be proud to be the party of wealth creation, unashamed to partner with the private sector.”
The Labour leader tried to make a merit of his honesty, saying: “Whether we agree or not, I will always treat you with the respect of candour, not the distraction of bluster.”