They're all struggling with the thorny question of how to lower public spending.
Do we save £1.2 billion by abolishing the interest subsidy on student loans? How about £1.3 billion by cutting back senior NHS wages? Or even £6.2 billion by freezing public sector pay for a year.
Wait a minute, what's this receipt here? £30 billion for a replacement for Trident? What's that you say? Plus a further £1.5 billion a year in running costs? Can't possibly cancel that of course. The ability to launch submarine-based nuclear holocaust is far more important than education, healthcare or the wages of people who provide public services.
Then again, £30 billion (plus yearly savings) would take a really nice chunk out of that £175 billion national overdraft...