Mr Tony Blair sank further in public esteem in September because of a failure to find weapons of mass destruction in Iraq and rising worries about the economy, according to a new poll.
The ICM/Guardian poll showed 53 per cent felt the invasion of Iraq earlier this year was unjustified against 38 per cent supporting it, and 9 per cent undecided.
The figures - based on telephone interviews between September 19th and 21st - showed opposition to the war had stiffened since July, when 51 per cent were in favour and 42 per cent against.
In April, immediately after the speedy invasion of Iraq by US and British forces, support for the war to oust President Saddam Hussein hit 63 per cent.
A public judicial inquiry into the death of scientist Dr David Kelly has revealed the intelligence community's doubts about the case for war, however, and exposed some of the machinations at the heart of Mr Blair's administration.
Support for the Conservative Party, which also backed the case for war, has fallen in tandem with the government since July, with both down by two percentage points.
With 35 per cent support, Labour still remains five points ahead of the Conservatives but only seven ahead of the Liberal Democrats, who captured a safe Labour seat in a by-election last week and whose support has surged six points since July.