The Treasury is assessing the case for the euro
Pro-euro MPs from all parties have stepped up the pressure on the government to call a referendum on UK membership of the euro.
The move comes amid speculation that Chancellor Gordon Brown is set to announce soon that the Treasury's five tests for joining the single currency have not been met.
Labour MP Chris Bryant, Tory Ian Taylor and Liberal Democrat Malcolm Bruce are delivering a bottle of champagne to Tony Blair along with a letter urging him to "have the bottle" to call a poll on the euro.
The MPs say the champagne will mark "the reasons to celebrate if we join the euro and the bottle needed to face down Iain Duncan Smith's 'no' lobby and call a referendum".
The UK's five tests
Convergence with eurozone
Enough flexibility to adapt
Impact on jobs
Impact on financial services
Impact on foreign investment
The move - arranged by the Britain in Europe campaign - comes ahead of a meeting of the cabinet.
The prime minister's team has yet to have a full discussion on the euro and there has been speculation that Thursday's meeting will cover the debate.
Mr Brown is reported to be keen to put off a referendum on the euro until after the next general election.
But Tony Blair is thought to be keen to see a poll within the next two years.
Trade and Industry Secretary Patricia Hewitt has said she has yet to see the Treasury's assessment of the five tests - which must be delivered before 7 June.
That has led some commentators to suggest that the outcome will amount to a "private deal" between Mr Blair and Mr Brown.
Pro-euro MPs have been pressing for a full cabinet discussion of the issue.
Mr Bryant, chairman of the Labour Movement for Europe, said: "If the prime minister just folds his hands now we risk political and economic isolation.
"What we need is leadership and determination - in other words, we want some bottle."
Ian Taylor, chairman of Tory Europe Network and The European Movement, described his party's anti-euro stance as "an aberration".
"Fortunately the many pro-European Conservatives who remain are prepared to work hard for Britain to join the euro as part of an all-party campaign," he added.
Mr Bruce said staying outside the euro would harm UK jobs, investment and industry.
"The Liberal Democrats have been warning of the damage our isolation from the euro would cause since the moment the new currency came into being in 1999," he said.
Earlier this week, Tory leader Iain Duncan Smith restated his opposition to the euro and called on the government to call a referendum.
Meanwhile, an inquiry by 11 economists into the consequences of rejecting the euro, sponsored by Britain in Europe, said remaining outside the currency could adversely affect trade and inward investment.
Mr Brown unveiled his five tests for joining the euro in 1997.
After the general election of 2001, he said they would be ruled on within two years of the poll triumph - creating a deadline of 7 June this year.
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There is no reason why we can't adopt the euro without relinquishing the pound
A positive ruling would spark a referendum on the euro.
The key economic test being examined by the Treasury is whether the UK economy has converged sufficiently with the eurozone and whether that convergence was sustainable.
The second test looks at whether there is sufficient flexibility in the UK economy to cope with economic change.
The remaining three tests assess the impact of joining the euro on jobs, on foreign investment and on the financial services industry.
Mr Brown will also publish 18 supporting studies alongside his euro decision.