Voters should use next month's European elections to protest against the war in Iraq, the Liberal Democrats said today.
The Party leader Charles Kennedy said the 10 June poll gave voters the ideal opportunity to tell Tony Blair that his actions had left Britain increasingly isolated in the world.
Launching the Liberal Democrats' campaign, Mr Kennedy said the Prime Minister had chosen to distance Britain from both the United Nations and the European Union.
"To govern is to choose," he said. "That political choice having been made on his (Mr Blair's) part, the European elections are the most appropriate forum in which to cast judgment over the wisdom of this Government.
"June 10 is a telling opportunity to send Tony Blair an unambiguous message. 'These days Prime Minister, over Britain's role in a sane world order, you no longer speak in our name. You appear increasingly isolated, Britain appears increasingly isolated. We are voting for something better'."
Mr Kennedy said, particularly over Iraq, people felt the Prime Minister was not listening to them.
He said the Euro poll was a particularly appropriate forum for protest because it was an election with an international dimension.
Liberal Democrat foreign affairs spokesman Sir Menzies Campbell said the decision to go to war was "in truth" the Prime Minister's, despite MPs voting in favour of it.
He said Mr Blair could not escape responsibility for the consequences of that decision.
"The central question of whether we went to war on a flawed prospectus has never yet been answered," he said.
"The weapons of mass destruction, which were the justification for the Government's argument that military action against Saddam Hussein was the only option, have never been found. And it is almost universally accepted that they never will be."
Sir Menzies said it was now clear there had been no proper planning for the aftermath of the war.
The Lib Dems will go into the election under the banner "Making Europe work for you".
Mr Kennedy said on top of the damage done by the war, Britain's standing had also been damaged by delay over the decision on joining the euro and the fiasco over the referendum on the European constitution.
The party will also focus on the environment during the campaign. Mr Kennedy said Europe had to act together to tackle pollution.
Among the proposals in the party's manifesto are a reform of aviation tax to support cleaner fuels and more efficient aircraft, the replacement of the Common Agricultural Policy with a food and rural policy and support for global ratification of the Kyoto agreement to cut greenhouse gases.
Decisions about whether to grow GM crops should be taken "using scientific evidence on the basis of the precautionary principle", the manifesto says.