Budget 2014

Tomorrow we have the 2014 budget. There have been a few pre-budget polls, but they don't really show us much we didn't already know: the public are increasingly optimistic about the state of the economy as a whole, but remain pessimistic about their own personal finances (though less pessimistic than a year ago). The Conservatives have a lead on the economy that has grown as the economy has started to recover, but Labour retain a lead on cost of living issues.

The graph below shows the impact of past budgets on voting intention polls. Up until 2009 they are the government's lead in the two YouGov polls before and after each budget, after 2010 and the advent of daily polling they are the average government lead in the daily polls in the two weeks before and after the budget.

Unlike most political events, budgets do actually have some cut through to the general public and do have the potential to change voting intention. You can see at least three budgets in the last decade that appear to have had a genuine effect on voting intention. In 2008 and 2009 Alistair Darling had to deliver grim news about the state of the economy and Labour's poll position suffered, in 2012 was the "omnishambles" budget, with the granny tax, pasty tax and the 45p tax rate. All three of those were negative effects, it's far rarer for a budget to have a positive effect (the apparent positive impact in 2003 was more likely the effect of the Iraq invasion).

The media often talk about budgets being an opportunity for fancy giveaways, a vote winning opportunity. The past data suggests that's rarely the case. More generally they seem to be bullets to be dodged. In theory I'm sure it's possible for a government to win support from a good news budget with popular policies, but in practice the general theme seems to be that a successful budget is one the government gets through without damaging their support.

Over the next few days we'll get lots of polling on the budget. As ever, treat it with some caution. One point to note is that budgets are often more or less than the sum of their parts: you can get budgets where the public support all the little changes and announcements made, but it still goes down badly overall (and vice-versa). The things to really watch are whether there is any change to people's economic optimism, to how well they think the government are doing on the economy, to which party people trust more on the economy and living standards, things like that... and, of course, voting intention itself.