The Chancellor George Osborne may be presenting his budget to Parliament tomorrow, but it'll be just as closely watched in another democratic building at the opposite end of the M4.
The Conservatives form the official opposition in the Welsh Assembly and its leader Andrew RT Davies knows that whatever he says is scrutinised for signs of difference with his Westminster colleagues. That's why he's been careful not to express too many opinions before the Chancellor makes his statement.
What he has said in public is that he and fellow Conservative Assembly Members have concerns about the possible impact of the introduction of regional pay levels in the public sector, something that's been predicted to feature in the Budget.
In fact those concerns were most recently raised at a meeting between the party's Shadow Finance Minister Paul Davies and the Chancellor.
Similarly the Welsh Liberal Democrats may be in opposition in Cardiff Bay, but their party shares government at Westminster and has a strong presence in the Treasury in the shape of Danny Alexander.
It's a relationship the party's Welsh leader, Kirsty Williams, is also eager to exploit. She says she and others have 'made representations' in private and formally to UK Cabinet ministers urging them against moving towards regional pay, saying that 'we would not support any greater moves towards regional pay.'
The prospect of regional pay and the implications it would have on Wales is also exercising Plaid Cymru. The party's Treasury Spokesman, Jonathan Edwards MP describes it as 'reverse London weighting,' adding that,
These proposals will institutionalise low pay in those regions and create employment ghettos where people will not wish to move because workers there will be forced into low pay and low ambition.
Meanwhile, the Welsh Liberal Democrats also wants to see faster progress towards the introduction of a £10,000 income tax threshold and a 'route map' with a timetable by when it would be achieved so that it would no longer be just an aspiration.
Ms Williams said,
I want to see a budget tomorrow in which those struggling to make ends meet pay less tax and those who earn more pay more tax.