"Blair hit by EU backlash," said The Sunday Times, pointing to pressure mounting on the prime minister from opposition politicians and business leaders to hold an immediate referendum on the constitution.
The euro-sceptic News of the World tabloid claimed that Blair was attempting to dupe the British public by delaying a plebiscite by up to two years.
"After his humiliating U-turn on holding a referendum to allow Britons a say in their future, he seeks to put back the vote, possibly to 2006," the newspaper said.
"Yet again, the premier misjudges the nation," it said. "If he believes he can fob off the electorate in this way, he must expect to pay a heavy price at the next general election", expected early in 2005.
In the biggest and riskiest reversal of his career, Blair pledged last April to put the constitution to the people in what will be the second nationwide referendum in British history.
An ICM poll (conducted for the New Frontiers Foundation independent euro-sceptic thinktank) showed that 57% of those asked in a referendum would vote against the treaty with only 28% in favour.
"Yet again, the premier misjudges the nation. If he believes he can fob off the electorate in this way, he must expect to pay a heavy price at the next general election"
News of the World
Only 28% said they believed Blair's promise that Britain will be able to keep complete control of its taxes, defence, criminal justice, and asylum policy, if it joined the constitution. Sixty-four percent said they did not.
Only 16% of 580 people polled on ICM on Saturday thought Britain should integrate further with other countries in the European Union.
Meanwhile, a YouGov poll of nearly 1,300 people for The Sunday Times showed that voters would reject the new constitution by 49 to 23%.
The anti-EU campaign, backed up by a like-minded popular press, feel emboldened after European Parliament elections that saw a fringe group, the UK Independence Party (UKIP), walk off with a dozen seats with its call for Britain to quit the EU altogether.
The Sunday Mirror tabloid said that Blair was so shocked by Labour's dismal showing in last week's local and European elections that he was considering delaying the next general election.
"May 2005 is still a possibility but only if things take a massive turn for the better," said a government insider quoted in the newspaper. "The case for 2006 is now much stronger."
Conservative leader Howard is
expected to call for a referendum
The News of the World and the Business newspaper said that some 28 of Britain's top business leaders had written to Blair on Saturday to announce a campaign against the constitution.
The Mail on Sunday said that 100 of Blair's own Labour MPs planned to rebel against the prime minister by forming a new anti-EU group called "Labour Against A Superstate".
"When people read the small print they will see that this takes us much closer to a Euro superstate," one of the rebels, former sports minister Kate Hoey, told the newspaper.
The right-wing Sunday Telegraph reported that opposition Conservative leader Michael Howard, whose party is dead set against the EU constitution, will call for an immediate referendum in the House of Commons on Monday.
The Mail on Sunday said that a referendum on the EU constitution provided Britain with a chance for the first time in 30 years to regain control of its national destiny.
"An emphatic national rejection of this document would draw a red line that could not easily be erased and would be, for once, a real victory over the Brussels juggernaut," it said.