CHARLES Kennedy stoked up the simmering dismay about Sir Menzies Campbell's leadership yesterday as he implied there was no excuse for the LibDem slump in the polls.

Speaking on BBC Radio 4's World at One, Mr Kennedy dismissed the suggestion that the LibDems faced a tougher challenge now because of changes in the wider political landscape, and he implied that their fortunes should still be improving.

In what was widely interpreted as a shot across the leader's bows, he argued that Gordon Brown's arrival as Prime Minister and David Cameron putting "flesh on the bones" of Tory policy plans had been "predictable elements".

Asked if he thought conditions were "harder" today than when he was leader and the party was doing better in the polls, he said: "No, I don't think so. There's nothing that has come as a surprise. It is nothing that should be fazing us at the moment."

Mr Kennedy refused to be drawn on his leadership intentions and, while he is not being considered as a serious replacement for Sir Ming at the moment, it is a matter of some conjecture that under Mr Kennedy's leadership the party's fortunes appeared to prosper better.

Sir Ming has no intention of creating a vacancy but seasoned observers predict his colleagues will wield the knife if the LibDems continue to do badly in the polls.

Sir Menzies took to the stage yesterday for a question and answer session designed to give voters and activists the chance to "get to know" the leader.

However, over the course of 45 minutes he joked about being a "failure" and appeared to confuse "Italy" and "India" when talking about emerging economic powers.

Staff at the Brighton Centre managed to exacerbate the situation by spelling his name as "Sir Menzeis Campbell" on the huge screen behind him.

Sir Ming insisted he was not too old to lead the party into the next election, and admitted that he had become "thick skinned" about the issue.

"It's not so much about age. It's about judgment and experience. It's about Liberal Democrat values and doing your best to promote them," he said.

Earlier, Jose Manuel Barroso, the European Commission President, was one of the star turns at the conference. Appealing to the LibDems to throw their weight behind the EU Reform Treaty, he assured delegates that the treaty was "not the constitution" and was not "full of hidden plots".

Timed to coincide with this speech, a group of LibDem councillors, organised by MP Mike Hancock, released an open letter calling for a referendum on the treaty but Mr Barroso argued that the EU should not be derailed by hostile anti-Europeanism.

He added: "We collectively need to demonstrate more concretely the benefits that membership of the European Union brings, that there's more to Europe than late night horse trading, that we are tackling the issues that matter to Europe's citizens."

Mr Barroso said the treaty was to make Europe's institutions "more democratic and more accountable".

"I strongly believe that the Reform Treaty is good for Europe and good for Britain. The treaty, including the hard-fought UK red lines, is not the constitution. I now hope that we can reach agreement in October and move swiftly to ratification," he said.

Sir Ming has already called for an "in or out" referendum on whether the UK should remain in the European Union. He argued that he did not currently believe the controversial EU treaty warranted a national vote on its own, but addressing the deeper issue would outflank Eurosceptics who are using the agreement as a focus for their arguments.

Mr Hancock said later: "This letter reflects much wider feeling in the party. Many people in the grass roots of the party think we should be putting pressure on the government to hold a referendum on the Constitutional Treaty."

Sir Ming accused Eurosceptics of "dreaming of an England that never was and a Britain that can never be".