You may have heard Human Services Minister Joe Hockey’s Canberra forecast on The World Today yesterday: “It’s a beautiful Canberra day. Bit nippy around here though.” Indeed. But we all kept snugly warm at the Crikey Tent Embassy with a bonfire made up from copies of the Ministerial Code of Conduct. We found them in a corner cupboard in Parliament House with their covers ripped off. No-one seemed to want them.

First light in Canberra today showed an interesting scene. Treasurer Dollar Sweetie gave an early morning doorstop where he said very little. What was more significant were the comments of Government MPs mugged by the meeja as they snuck into the House. Queensland Warren Entsch, for example, said that there are no ministerial positions in opposition. That’s the issue here in Canberra. It’s Budget day, but it feels more like a leadership spill. Not even Paul Keating’s last hurrah had the same atmosphere.

Today is different from other post election Budgets in other ways, too. They’re normally slash-and-burn affairs, but with estimates of the surplus running from $6 billion to as high as $13 billion, who knows what Peter Costello might have to please the punters.

He needs something after his poor polling in today’s Fairfax broadsheets – Kim Beazley beating him as preferred prime minister 50% to 41%, Labor leading the two party preferred vote 51% to 49% and a significant 63% of voters saying they expect John Howard will serve out a full term. All that, just one day after similar results from Newspoll. It calls for some sort of Lady Bracknell remark.

That’s why that surplus figure is so interesting. No matter what the final figure, much of it is windfall. Tax windfall.

We’ve heard plenty about welfare to work measures, about clampdowns on sole parents, disability pensioners and dole recipients that will be announced tonight. They’ll be harsh medicine, but are designed to push people off the welfare books and maybe even into the position where they’ll actually be topping up, rather than reducing, the government’s coffers.

It’s the tax cut angles that are more interesting. Peter Costello – let alone John Howard – would never, ever dare to do a Harold Macmillan “this is as good as it gets” act, but that might be the case. Will Dollar Sweetie be able to play the nice guy? Does he have enough room to give us some across-the-board tax relief or raise the income tax threshold? Will there be something for everyone tonight?

So much of the Budget has been leaked, hinted at, or raised in worse-case scenarios already, in the hopes that we’ll be left smiling – or at least not scowling – when we see it all in context tonight. There’s room for surprises – but if Peter Costello wants to be prime minister sooner rather than later, they’d better be surprises that leave us with a smirk almost as broad as his.