I Know Why the Caged Bird Sings

Because nobody-- nobody-- likes the prospect of years in prison.

Singer explains:

Now, what is so interesting about Wurmser and Hannah? Wurmser and Hannah both worked under John Bolton before being “loaned” to Cheney’s office. They’ve also been identified as likely being the two administration officials responsible for the original leak. Interestingly, they were also both in a position where they likely would have known Plame’s covert status.

In other words, they may have very good reason to turn on their bosses. If Fitzgerald had evidence that they violated the Intelligence Identities Protection Act, they’d be in big trouble. But no one looking at that situation could really believe that these two operatives acted without the knowledge and direction of others higher up the food chain...

Let’s just look at it this way, two of Cheney’s aides are cutting a deal and not for immunity either. That means they were in serious trouble. It also means that they have information worth letting them off the hook.

This doesn’t all add up to no story.

It now adds up to two inside sources implicating Cheney’s office.

Wurmser and Hannah have also been around long enough to know that it's the Administration's MO to blame low-level underlings for higher-up screw ups (witness Abu Ghraib). They knew that if they hung together, they'd probably end up hanging alone.