By Guto Harri
BBC News political correspondent
Europe could dominate and sour the next Parliament.
Will joining the EU still be a cause for celebration in the future?
It could determine the timing and manner of Tony Blair's departure from Downing Street.
It could give Michael Howard something to hang on for - if he loses the general election.
And a referendum, promised by all parties, will define Britain's relationship with the EU for a generation.
Yet, bizarrely perhaps, Europe is not likely to feature prominently in this campaign.
"It's not one of our ten words," a Conservative party official told me.
Check out the Conservative website, and you'll see what he means.
The Tories spent years tearing themselves apart over Europe, but it is no longer a stated priority in government.
IS IT DEVOLVED?
Scotland: Not Devolved
Wales: Not Devolved
NI: Not Devolved
Devolved issues are the responsibility of the Scottish Parliament, Welsh Assembly, or NI Assembly
Their five neat pledges, of two words each, do not mention re-negotiating treaties or saving the pound.
"What we will do" involves taxes, schools, hospitals, crime and immigration, but Europe will be buried where it belongs - in the body of their more detailed manifesto.
The spectacle of William Hague counting the days until Britain surrendered the pound sterling will not be repeated, not least because the public (still using the pound) would not believe it.
All EU leaders face tough choices on the constitution
Do not expect much talk of Europe from Labour either.
Tony Blair promised a referendum on the European Constitution to defuse its explosive potential on polling day.
Why waste time arguing about it now, when you've been promised a chance to vote on it next spring?
As for the euro, even journalists have grown tried of being told we have to wait for another assessment of the five economic tests.
Any answer that leads to those tests will leave you lost in the long political grass.
Four years ago, Labour went into the election arguing that Europe should be seen as an "opportunity" rather than a "threat".
They carried out an assessment of the five tests - as promised - early in this Parliament.
The debate on euro membership has cailmed down
Pro-Europeans were disappointed when the chancellor failed the euro on four counts, but Gordon Brown had never promised it would pass.
Some Labour supporters felt let down, even cheated, but the party basically kept its word.
Britain's relationship with Europe was, of course, far more of an issue than the manifesto commitments had implied.
War in Iraq pitched Tony Blair against some of his closest traditional allies, and soured the mood of many a meeting or summit.
EU enlargement went ahead and was celebrated, but new members found themselves forced to choose sides.
US Defense Secretary Donald Rumsfeld mocked the "Old Europe" for opposing his war, pushing former communist countries to embrace his "war on terror" as proof they'd really moved on.
On the eve of enlargement, there was also much hysteria about a potential surge in immigration from the new member states, with journalists heading east to intercept them and feed the fear.
Promise of Referendum
The Conservatives put Labour on the back foot, and made much capital of Tony Blair's refusal to grant the people a say on a new EU constitution.
Whether the treaty is a "tidying up exercise" or a significant "surrender of sovereignty", Conservatives used the issue to highlight what they called Tony Blair's arrogance.
Sensing the danger, the Prime Minister, surprisingly and rather awkwardly agreed to a referendum before finally agreeing and signing the package.
Liberal Democrats had also pushed for a poll, although they want the constitution ratified as soon as possible.
They have also been pushing for an early vote on the euro, and have suggested both polls could be held simultaneously in the next Parliament.
Plaid Cymru will also press for a yes vote on the constitution, though the SNP object to fishing being declared an exclusive concern of the EU.
Both nationalist parties still have the long-term goal of seeing their respective countries join the EU as independent members.
No one would bet on a yes vote this week, which is why the UK Independence Party is the only major force whose candidates will be concentrating on this issue over the next few weeks.
That will change swiftly when this election is over.
Britain will hold the EU Presidency later this year and will therefore have to face the most difficult issues head -on.
Later in the Parliament there'll be rows over sensitive issues like the UK's rebate, and the moment of truth will arrive on the referendum on the EU Constitution.
The referendum could crush euro-scepticism once and for all, or make it clear beyond doubt that most people here feel the EU has taken over too much sovereignty.
Even if Labour wins the General Election, losing the referendum could signal the end for Tony Blair, and possibly Charles Kennedy.
And even if he doesn't make it to Downing St, winning the referendum would allow Michael Howard to leave politics on top, or to hang on for another election where more than a decade of Labour rule could at last be reversed.
The stakes are high, so we can expect two campaigns to kick off almost immediately.
Interestingly, Labour's lease on their current campaign headquarters lasts well into next year.