A combination of rising inflation, spending cuts, benefit changes and tax rises risks creating "a cost-of-living crisis" for families, Ed Miliband will warn tomorrow.
The Labour leader will concede that over the past 20 to 30 years the "once-safe assumption" that the proceeds of growth would benefit most people on middle incomes has been eroded.
But in a major speech at the launch of the Resolution Foundation Commission on Living Standards, he will accuse the coalition of making the problem worse. Mr Miliband will warn that the "British promise... that the next generation would always do better than the last is under threat like never before".
Also on Monday Lord Mandelson will launch a revised edition of his memoirs, The Third Man. In it, he claims Mr Miliband has yet to set out a "powerful" vision, adding that if he fails Labour will again be "distrusted on the economy and taxation".