Being Prime Minister isn't supposed to be easy, but even Tony Blair's harshest critics might concede he was set an impossible challenge yesterday.

He was asked "to create a world where there is no longer war or conflict".

This modest request, during Prime Minister's Questions in the House of Commons, came from the respected figure of John Hume, the former leader of one of the Northern Ireland parties.

It just goes to show that people have high expectations. The election campaign must be a relief to Mr Blair. Nobody expects him to do anything at all for the next six weeks, except fly around in his helicopter and call Michael Howard names.

Yesterday was the last of the big set-piece clashes between the two party leaders before the Commons is dissolved by the Queen.

But this isn't a spectator sport. Both Mr Blair and Mr Howard have their supporters, who see it as their duty to join in.

The Conservative benches were in a raucous mood. Cheerleaders included Peter Luff, the Mid Worcestershire MP and a Tory whip, who had chosen to stand in an aisle rather than sitting on one of the green benches.

From there, he pointed at the Labour MPs and laughed out loud at what, it was clear, he considered to be their foolishness.

Mr Howard and Mr Blair went through their double act. You introduced tuition fees, said Michael Howard! Ah, but you introduced the poll tax, retorted Tony Blair!

We'd heard this routine before. But Mr Howard had added a new line. Time and again, he asked Mr Blair: "In the words of the Chancellor, why should people ever believe him again?"

This is what the Conservative election campaign is really about. Not tuition fees, or hospitals or immigration, but Tony Blair and whether he can be trusted.

To prove his point that Mr Blair was a liability, Mr Howard asked Labour MPs whether they were sticking the Prime Minister's smiling face on their election leaflets.

The Conservative benches erupted, as Tory backbenchers revealed that they intended to focus on Mr Blair as much as they could. Michael Fabricant, Tory MP for Lichfield, stuck his hand in the air and bounced excitedly in his seat.

But then they grew more animated still. A few Labour MPs had actually fallen for Mr Howard's ruse, and put their own hands in the air to confirm they were loyally backing the Prime Minister.

The trouble was that there were only six of them. Conservative backbenchers pointed and shouted with glee: "Six! Six! Six!"

Labour MPs were in a similar mood, mind. When the Liberal Democrats finally had a chance to talk, Labour backbenchers pointed at them and asked: "Where's Paul? Where's Paul?"

They were asking about Paul Marsden, the Shrewsbury and Atcham MP who was elected as a Labour candidate and defected to the Lib Dems in 2001, only to "re-defect" back to Labour this week.

So this is the House of Commons - complete with jeering, shouting, fingerpointing and silly jokes, and just a dash of idealism.

Some of the nation's best brains will spend the next six weeks in a desperate fight to be a part of it.