Most people have very little interest in politics.
If you are reading political blogs you are probably an exception, but most people cannot name more than half a dozen MPs. If you can name several Lib Dem front benchers then you are probably in the most politically informed 5% of the population. If you know what a front bencher is then you are in the top 50%.
The Times reports that most voters have completely misattributed which policy each party has on VAT despite it being the main focus of discussion for the first week of the campaign, this echoes what I found from personal experience in relation to another area of policy.
Basically almost nothing that is said over the next few weeks will have any impact with the voters and what does have an effect will probably not be in the way that might be predicted.