Five Cabinet ministers have privately expressed concern following Labour's defeat in last week's Euro elections that the Government has failed to sell its policies to working-class voters. They are worried that Mr Blair's constant attempts to woo Middle England have alienated voters and Labour activists in the party's strongholds.
The ministers are understood to include Jack Straw, the Home Secretary; John Prescott, the Deputy Prime Minister; David Blunkett, Secretary of State for Education; Mo Mowlam, Northern Ireland Secretary; and Clare Short, International Development Secretary.
As the Cabinet discussed Labour's disastrous Euro election performance yesterday, Margaret McDonagh, the party's general secretary, warned in a memo leaked to The Independent that Mr Blair cannot take a second term for granted.
"The coalition of voters that elected Tony Blair is fragile," she told staff at the party's Millbank headquarters in the wake of the defeat. "There has never been a solid, left-of-centre majority in this country.
"We won in 1997 because we won back people who hadn't voted Labour for years and have such a big majority because we attracted people who had never voted Labour before. Our task is to make these people see themselves as `Labour', " she said.
"We must not allow ourselves to become out of touch. The Tories did that and the voters punished them for it."
Mr Blair told the Cabinet yesterday that Labour's defeat was a "timely reminder" of the need to avoid complacency and "the importance of constantly building and keeping the support of the people for what we are doing." But he insisted the Tories had made a long-term error by running a hardline Eurosceptic campaign.
Cabinet ministers believe Mr Blair has privately conceded the Government must step up its efforts to explain policies that benefit lower income groups, such as the national minimum wage, the 10p starting rate of tax, child benefit rises and the working families' tax credit.
"We are not saying the policies are wrong, just that we are not highlighting them," one Cabinet source said last night. "This is a serious problem."
The minister said: "Harold Wilson won a landslide in 1996 but we lost in 1970 because the working-class vote did not turn out. There are worrying parallels."
There is growing concern in the Labour hierarchy that party members are disenchanted. "In 1997, our activists were motivated because they wanted to get rid of the Tories," one said. "Now they are disaffected."
Downing Street denied reports that Ian McCartney, the Trade and Industry Secretary, would lead an inquest into the poor results. He is tipped to become party chairman when Mr Blair reshuffles his Cabinet next month.
Blairite moderates are believed to have regained a seat from the left in the annual elections to Labour's National Executive Committee, to be announced next week. Last year left-wingers won four of the six seats representing constituency parties.