A poll of thousands of Britons has found almost half the public see Tony Blair as George W Bush's "lapdog".
Only 13% of the public back military action against Iraq, with 9% definitely opposed, but 76% are still open to persuasion.
Mr Bush is viewed as a greater threat to world peace than Saddam Hussein by one in three of those still undecided about the merits of military action.
The poll for a Channel 4 News special programme suggests that Mr Blair's biggest obstacle to winning over public opinion in favour of military action is his ally Mr Bush.
When given a straight choice between the two leaders, some 32% of the undecided said Mr Bush posed the greatest threat to world peace, compared with 49% who named Saddam Hussein.