By Nick Assinder
BBC News Online political correspondent
It may not be a general election, but "Super Thursday" on June 10 is the next best thing.
The local council, European parliament and London assembly elections represent a huge test of popular opinion.
Blair's future is matter of speculation
They will provide a dry run for the big one which is still expected to come in a year's time, on the day of the next local elections on 5 May - already being dubbed 05 05 05.
And their outcome will set the tone for the general election campaign to come.
They could even transform the political landscape in the run up to that poll.
For Tony Blair, the elections could prove crucial for his leadership and, many believe, may well even decide his political future.
Any suggestion that voters used the poll to register particular disapproval of his leadership will have profound consequences.
He was always likely to be safe in his job for as long as Labour backbenchers believed he was an electoral asset and would help them hold onto their seats in the general election.
If the local polls suggest he has become an electoral liability, his future will once again be a matter of intense speculation.
Howard must improve Tory showing
The Labour campaign is almost certain to boost Gordon Brown's standing because of its concentration on the economy and unemployment.
And, on the very day the campaign was launched, former Labour Chancellor Lord Denis Healey fanned the speculation by saying Mr Blair should stand aside in favour of Mr Brown before the general election.
It follows recent comments by former party leader Neil Kinnock who suggested the prime minister may consider "hanging up his boots".
The Tories have seized on all this to target Mr Blair, particularly over the issue of trust.
They will claim the prime minister has lost the confidence of voters who are increasingly disillusioned with the government and its record.
This is difficult territory for Mr Blair. There are signs things may well be improving in public services but voters remain to be convinced these are widespread.
But it is also difficult for the Tories. There are real fears that if they are too successful in undermining Mr Blair, they may find themselves facing Gordon Brown leading a revitalised Labour party at the next election.
For Michel Howard, the elections are the biggest possible test of his leadership outside a full-blown general election.
His party is starting from a relative high after doing well in these same elections last time around.
Blair brands Howard "Thatcherite"
But the Tories will need to further improve their performance - by taking some key councils, for example - if they are to prove they really are on the way back to power.
By any measure, Michael Howard has had a pretty successful leadership so far - particularly when compared to his predecessors.
But he has still to prove that this represents a sustainable improvement that will put him in real contention at the next general election.
As indicated by Tony Blair at his campaign launch, Labour will continue concentrate its fire on his past record as a member of Margaret Thatcher's government and his part in the introduction of the poll tax and increased unemployment, for example.
And the Labour poster - which borrows heavily from two previous Tory election campaigns - suggests there will be a negative side to its campaign.
Of course, no matter what the polls end up saying about the parties, all sides will need no reminding that
the results can not be seen as an indication of how people will vote in the general election.
It may well be that voters use them to give Tony Blair a thumping - but then go on to elect Labour for another term in a year's time.
It has, after all, happened many times before - just ask William Hague.