Conservative leader David Cameron goes on the attack - saying the only decent ideas in the budget were stolen from his party.
He makes this about politics too. He tells the commons there should be an election now. Well he doesn't have long to wait.
One political pollster tells me that the political budget should play well with voters.
The pollster said: "Alistair Darling has made the case for keeping on the same path to recovery.
"The Conservatives have been thrown onto the back foot and will now need to explain to voters how they would make things better".
13.28 GMT
And he's done. We got the usual increase in sin taxes (alcohol, tobacco) and a plan for a new green investment bank which was heavily trailed.
But this was an exceptionally political budget. It was designed to play to Labour's core voters, to make a clear distinction with the Conservatives and convince the public that there should be no change in how the economy is handled.
13.00 GMT
Darling cuts stamp duty - the tax on house buying. He raises the limit when the tax kicks in from $190,000 to $375,000 for first time buyers.
He'll pay for this by raising the tax for those selling a home for more than $1.5m.
This will be seen as a tax on the rich and will play well with Labour's core support.
12.45 GMT
Darling outlines where the government has brought in more money than expected through bailing out the banks and a tax on their bonuses.
He insists there has to be better regulation of the financial sector.
He announces a scheme to give everyone in the UK access to a basic bank account - that move had been widely leaked.
12:30 GMT
All the politicans that were lurking outside parliament have now disappeared - heading inside to hear the big set piece for themselves.
Gordon Brown has just sat down after taking questions. Now it's all attention on Alistair Darling and the big budget statement.
He starts saying the right calls were made during the global financial crisis and tough choices lie ahead. A general statement on what he'll do, now the details.
11:45 GMT
Finance Minister Alistair Darling has left Downing Street.
He's done the traditional photo call - hoisting the old battered red box up and smiling.
There's a tingle of excitement through the expanding media village outside Westminster. Even jaded old journalists who must have been through this dozens of times seem quite excited.
Two helicopters circle above the Commons, news crews following the short journey from the finance minister's office where he'll deliver the budget shortly.
11:30 GMT
The Cabinet's been told about the budget and now a few of them are out telling the media how wonderful it's all going to be without going into detail.
"All will soon be revealed" they say but it shows how keen Labour is to spin this, to win the PR battle.
This is as much about the election as the economy.
I spot Douglas Alexander, the international development minister - a man who will play a big role in planning and running the upcoming election campaign.
I ask what's in the budget. He smiles but tells me that this is a budget which moves from fighting the problems of the financial crisis to recovery and growth.
I ask if the budget is constructed with the election in mind rather than the economy. He's bullish and insists the voters will reward governments which do the right thing.
10:30 GMT
There are little huddles of politicians and journalists all around Westminster giving their opinions on how things are going to develop over the next few hours.
I get the sense that no matter what Alistair Darling does, the Conservatives, the main opposition, have already decided they'll hate it and the third biggest party, the Liberal Democrats, won't be sitting back expounding theories of Alastair Darling's brilliance either.
He must walk a fine line. He's got to reassure the markets Britain is serious and has a plan to get the debt under control.
And at the same time he's got to give the voters a sense not just that things will get better but when and how.
9:30 GMT
Alistair Darling will have to cross a picket line to deliver his budget. A handful of striking civil servants are gathered outside the Commons, protesting at planned changes to pensions and payoffs.
8:30 GMT
The green outside Westminster is filing up with TV crews and journalists who'll be following the events today.
Alistair Darling has made a pre-budget statement which has been posted on YouTube. I can't remember anything like that every happening before.
Normally there's complete silence from the Treasury in the run-up to the budget.
To a degree there's an element of fantasy politics to this budget.
Alistair Darling will outline how he hopes to drag Britain out of its almost stunning indebtedness, where he'll make cuts, how he'll raise revenue, but he might never get the chance to put it in to practice.
A general election is just a few weeks away.
A win for the Conservative opposition means there'll be a completely different
budget, a completely different approach.
A minority Labour government would mean it could need the support of the smaller Liberal Democrats to govern, and that means a different budget too.
And should Labour upset the opinion polls and win a majority, who would bet on Mr Darling keeping his job.
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