UK: The Conservatives and the United Kingdom Independence Party (UKIP) have warned the Prime Minister Mr Tony Blair he has "no mandate" to endorse the new EU constitution in Brussels later this week.
However, Foreign Secretary Mr Jack Straw has insisted Labour can still win a referendum on the constitution despite the Eurosceptic surge in Britain's European Parliament elections.
Final declarations yesterday left the UKIP in third place behind Labour and ahead of the Liberal Democrats with 16.1 per cent of the vote and 12 MEPs. The Lib Dem leader Mr Charles Kennedy was still able to celebrate an increase in his party's share of the vote (14.9 per cent) and its representation (up 2 seats) from 1999.
But the results spelt a second drubbing for Labour, after last week's unprecedented third place in the English and Welsh local elections.
Although relieved to hang on to second place this time, Labour lost six seats (with the figures adjusted to allow direct comparison with the 1999 results) while its 22.6 per cent share of the vote was the party's lowest since the first World War.
Labour's only consolation was to argue the results were "even worse" for the Conservatives who "won" the election but lost eight seats, while recording their lowest share of a national vote - 26.7 per cent - since 1832. With the governing party and principal opposition failing to command a full 50 per cent of the vote between them, the UKIP claimed the outcome marked "a sea change" in British politics.
The party's star turn Mr Robert Kilroy Silk - who took the UKIP to within 0.3 per cent of beating the Tories and topping the poll in the East Midlands - predicted the Conservatives would now have to shift to a more hardline position on Europe.
Speaking on the BBC's Today programme Mr Kilroy Silk - who later suggested the UKIP could "wreck" the European Parliament - insisted that many Conservative voters also supported withdrawal from the EU.
"Clearly the Conservative Party is highly Eurosceptic, and is probably coming increasingly towards the UKIP line on this particular issue," he said. Conservative foreign affairs spokesman, Mr Michael Ancram, denied his party would be forced to shift policy in response to the UKIP's success, insisting it would impact only "in the sense that we are going to have to make sure people understand we do want to try to reform Europe so that Europe works better.
"We have made it clear we don't want to leave Europe." However - as the UKIP launched a poster campaign ahead of the Brussels summit with the personal message to the prime minister: "Don't sign the constitution, Tony. Britain says No" - Mr Ancram signalled the political battle ahead.
Speaking on the same programme he said: "If you look at the UKIP vote, yes there are people voting for it who want to pull out of Europe. But there are equally people who voted to give a signal that they wanted to see a firmer stand taken against the way Europe is going at the moment."
He continued: "I hope if there is one message Tony Blair takes out of this it is that he has no mandate to go to Brussels and sign up to this wretched constitution."
A Downing Street source dismissed this assertion as "absurd" saying that, since Mr Blair had promised a referendum, "the only relevant mandate will be the people's."
Meanwhile, Conservative leader Mr Michael Howard signalled a shifting focus back to domestic issues yesterday as he conducted a limited reshuffle of his shadow cabinet.