The Week in Politics: This is a referendum on Iraq, Tony Blair - and Michael Howard

When Charles Kennedy called for the election to be a referendum on Iraq, a close ally of Tony Blair told me, to translate it politely, the Liberal Democrat leader was spitting in the wind. As the campaign enters its final lap, Mr Blair can no longer be sure about that.

When Charles Kennedy called for the election to be a referendum on Iraq, a close ally of Tony Blair told me, to translate it politely, the Liberal Democrat leader was spitting in the wind. As the campaign enters its final lap, Mr Blair can no longer be sure about that.

I have been struck by how often the word "referendum" has been bandied around by all three main parties as they try to shape the election debate.

The Tories want the election to be a referendum on Mr Blair; Michael Howard rarely speaks about "the Labour Government" but scathingly blames everything on "Mr Blair". Presumably, his party's polls tell him that "Labour Government" is a more popular than "Mr Blair".

Labour's strategy is to prevent the election being a referendum on its eight years in power. Instead, Mr Blair has cheekily tried to turn it into a referendum on something else: whether the Tories are fit for office.

A week ago, it looked as though he was succeeding. Even the Tories' best issue - immigration - was starting to hurt them, a luxurious position for Labour to be in. Now the picture looks very different. After the partial leak and full publication of the Attorney General's advice on the war, and the defection of Brian Sedgemore to the Liberal Democrats, Labour strategists are wondering whether they are living out their nightmare scenario: an election overshadowed by Iraq. They are desperate to move on the economy and public services between now and Thursday.

Mr Blair hopes the voters' appetite for more minutiae about Iraq is satisfied and most people made up their minds on the issue long ago. But I suspect many voters are still agonising about whether they can bring themselves to vote for "Mr Blair" because of Iraq. That is why the past week is dangerous for Labour, and why it now wants to keep the issue out of the headlines.

The more the spotlight is on Iraq, the more Mr Blair's lines look unconvincing. He is glad that Saddam Hussein is "in prison rather than power". He has retrospectively moved the goalposts towards a policy of regime change in Iraq. But Lord Goldsmith's initial advice says starkly: "Regime change cannot be the objective of military action." Nor can Mr Blair's line be squared with his warning on the eve of war, that Saddam could still save his regime if he disarmed.

The focus on Iraq has undoubtedly helped the Liberal Democrats. They were wise not to play their best card too early. They had a lacklustre start and were frustrated not to have a higher profile. That was partly their own fault, as they ploughed their own furrow too often. On the day when the crime statistics were released, the issue was bound to dominate the election coverage. Yet the Liberal Democrats were talking about tuition fees.

However, the leaks and Mr Sedgemore's defection gave the Liberal Democrats momentum at a critical stage. I thought Charles Kennedy won the battle between the three leaders when they appeared separately on BBC TV's Question Time on Thursday. Labour's own trump card, perhaps, is our wacky electoral system: there can only be one of two prime ministers on Friday -- Mr Blair or Mr Howard. For all their reservations about Mr Blair, people still prefer him to the Tory, whose decision to run a virtually one-man show is a mistake. Some pollsters believe the more people see of Mr Howard, the more they dislike him.

The suspicion is fuelled by a rolling poll by the the British Election Study at Essex University. Mr Blair has overtaken Mr Kennedy as the leader doing the best job in the campaign, presumably as voters focus on the real choice. Mr Howard has slipped back.

The Tories' polls show that their " Blair liar" gibe hit home. But people believe all politicians are liars, so they are very sceptical about the limited promises Mr Howard is making.

But the race feels closer than the opinion polls, which may not do justice to the three very different elections which are being fought in different seats - Labour versus Tory, Labour versus Liberal Democrats and Tories versus Liberal Democrats.

Some ministers I trust privately predict a Labour majority of 50, which would be seen as a disappointment rather than a triumphant third victory. It would also cut short the three-and-a half-year Downing Street tenancy Mr Blair hopes to secure next Thursday.

Iraq is also a reminder of what happens if one party gets too big a majority. My hunch is many people want Labour back - but with a small majority. The problem is it is difficult to ensure that within the straitjacket of our electoral system.

However, the voters may be more clever than the politicians think. The beauty of the coming week is that all the polls and focus groups in the world cannot tell them what will happen.

The leaders may have made their pitch for the election to be a referendum on Iraq, Mr Blair or the Tories. But on Thursday they will, for a day, be powerless, and the voters will make it a referendum on whatever they want.

a.grice@independent.co.uk