Chris Mullin, the chairman of the powerful Commons select committee on home affairs, said: "I wish we were not so dependent on spin doctors or the favours of rich men. We won on sleaze. We could lose on sleaze."
But in a strongly supportive speech to a left-wing group of Labour supporters, Mr Mullin also praised the Blair government's achievements.
"There are some signs in the last few weeks that the bubble may be about to burst but, by and large ... voters are much happier with this Labour government than [are] party members, or at least those who are active."
He said it should not have built the Millennium Dome; it should not have been necessary to make "a Faustian pact with the middle classes over taxation"; and he attacked an "unhealthy authoritarian streak in New Labour".
But there were 10 areas where it had made progress, including the minimum wage, he said. His support for Mr Blair came after the former Labour leader Neil Kinnock weighed into an increasingly sour battle for places on the party's governing body with a warning to activists not to elect "Trotskyites, sectarians and other selfish parasites".
Mr Blair's supporters are expected to be defeated by some on the hard- left in the elections to the National Executive Committee (NEC) to be announced at the party conference in Blackpool at the end of the month.Reuse content