The Liberal Democrats have said they are committed to tackling issues such as environmental protection and crime in partnership with other governments.

Talking to ePolitix.com as the campaign continued at the end of May, senior MEP Graham Watson said his party was also committed to making the European Union "work better".

"That doesn't mean that we are starry eyed federalists and we do believe that there is a case for continuation of what some people would call the national veto in certain policy areas," said the Lib Dem leader in the European parliament.

"In other words we want a clear definition of which policies can be decided and which policies are more rightly the province of the member states.

On the euro, again we are clearly in favour. We think it would be good for Britain’s economy to be in. We believe that the chancellor should be setting a target date for a referendum on the euro."

He said that voters could make up their minds on the basis of events in Iraq, but said there were also other issues playing a role.

"Essentially it is a very clear choice. Society faces a number of supra-national challenges which require a supra-national response," Watson told this website.

"I think of challenges like population growth and immigration, challenges like internationally organised crime, challenges like the environment.

"If you vote UKIP or Tory you are effectively voting to pull the blankets over your head and wish that these challenges would go away. Because these people are the wreckers in Brussels and Strasbourg.

"If you vote Labour you are voting for American leadership, which sometimes means the American dimension in Iraq.

"Whereas if you vote Liberal Democrat you are clearly voting to make the European Union work properly and efficiently both at home and abroad."