By Peter Griffiths
LONDON (Reuters) - Britain's Labour leader Ed Miliband will stake his claim to replace Prime Minister David Cameron at the 2015 election on Tuesday with an attack on government cuts that he blames for the longest fall in living standards in more than a century.
Miliband will try to improve his disastrous ratings and convince voters they can trust his opposition party with the economy, accusing Cameron of prolonging the recovery from its worst crisis since World War Two.
In a speech to Labour's annual conference, Miliband will cast Cameron's Conservatives as the party of the rich and say only Labour will help families and small businesses bruised by years of stagnation, public cuts and weak wage growth.
Miliband, who beat his older brother to the leadership in 2010, will hope to silence party critics who want him to deliver a clearer message to voters and do more to be seen as a future prime minister.
"We have the slowest recovery in 100 years, one million young people looking for work...the longest fall in living standards since 1870," he will say, according to advance extracts of the speech.
"They used to say a rising tide lifts all boats. Now the rising tide just seems to lift the yachts."
Center-left Labour, which has a narrow lead over the center-right Conservatives, lost power in 2010 after the party suffered its second worst election defeat since 1918.
Labour's economic reputation was shredded by the financial crisis and a period of high borrowing and spending that led to a record peacetime budget deficit just before their defeat.
Labour says it will have "iron discipline" on spending and Miliband will warn supporters that he "won't be able to spend money we don't have".
If Labour wins the election, one of Miliband's first acts will be to stop a planned cut in the rate of corporation tax in 2015 and use the money to help small companies, he will say.
Miliband, 43, whose Marxist father escaped the Nazis in Belgium by catching one of the last boats to Britain in 1940, is trying to restore economic credibility and lift his personal ratings at Labour's meeting in Brighton, southern England.
Supporters say he is a strong figure who united his party after years of feuding, blocked Cameron's support for military action in Syria and became the first party leader to refuse to kow-tow to media bosses like Rupert Murdoch.
Detractors, however, dismiss him as "Red Ed", a left-wing figure who lacks gravitas, struggles to convey his beliefs and whose style alienates voters.
One of his biggest obstacles is the persistent message from opinion polls that voters have more faith in the Conservatives to run the world's sixth biggest economy.
Signs of a surprisingly strong recovery have allowed the government to boast that they have won the argument about how to secure the recovery.
Under the slogan "One Nation Labour", Miliband's speech will paint the Conservatives as an uncaring elite that has divided Britain.
Miliband will distance himself from the centrist, pro-business line pursued during former leader Tony Blair's New Labour project by saying too many economic benefits are "scooped up by a privileged few".
"David Cameron and (finance minister) George Osborne boast that they fixed the economy, but for hard-working families life is getting harder not easier," Miliband will say.
(Editing by Angus MacSwan)