On the Republican convention stage tonight, you're going to see a really large clock. But the clock isn't for keeping time. The idea isn't to stop speakers from going over their allotted time, or the convention from running late. It's a debt clock. And the idea is to blame President Obama and the Democrats for the national debt.
But in doing so, the Republicans will end up blaming Obama for the policies they pushed in the Bush years, and the recession that began on a Republican president's watch, and a continuation of tax cuts that they supported. They'll have to. Because if they took all that off the debt clock, there wouldn't be much debt there to blame him for at all.
The single thing you should look at to understand the debt clock and what it is - or isn't - telling you is this graph from the Center on Budget and Policy Priorities. It does something very simple. It takes public debt since 2001 - which is when we last saw surpluses - and breaks it into its component parts.