Like him or not, spare a sympathetic thought for David Cameron today. If he is anything like Tony Blair when Leader of the Opposition, he will have woken up this morning with the sense of a very big challenge ahead of him for the day.

He does that every Wednesday of course, because Prime Minister’s Questions is always an important part of the Parliamentary week. But today the workload is doubled, tripled, quadrupled and more, because as well as doing PMQs, he has to respond to Alistair Darling’s Budget. ‘If there is a bigger nightmare than responding in these big set piece Parliamentary debates, I’ve yet to find it,’ TB used to complain.

And whereas at PMQs, at least the Leader of the Opposition knows what he is going to ask, with the Budget it is the Chancellor who has the advantage, in knowing what it is to come.

The broad outlines of Cameron’s response will already be written, but he does have to think on his feet, and respond to specific announcements.

A word of advice … Ignore all the last minute speculation doing the rounds this morning, focus on big arguments and try to respond to what Alistair actually says. Also, try very hard not to think too much about the bumbling, stumbling, rambling, incoherent interview you gave with Gay Times, which looks set to become an instant Youtube hit.

All Budgets are important moments, but the proximity to the election makes this even more so.

The House of Commons is often the place where the dividing lines of the campaign are first laid down. Some of the arguments today will be familiar, some less so.

But though Cameron gets the first word, the heavy lifting will thereafter done by shadow chancellor George Osborne.

Spare a thought for him too. He appears to be unpopular with the public, unrated by the City and business leaders, and a bit of a whipping boy for Tory MPs and candidates forever reporting his unpopularity back from the doorsteps and businesses.

Alistair Darling on the other hand has emerged with his authority and credibility enhanced from the post economic crisis phase.

He has always been likeable. But in politics that is sometimes less important than respect. When he stands to deliver the Budget today, his basic economic credibility is not really an issue. The same cannot be said for DC and GO. George Osborne. Game On.

Here’s more from Channel 4 on the Gay Times interview by the way.

* Buy The Blair Years online and raise cash for Labour