Am I thinking right?

[hamjet]

When I try to start my 69 pickum up, it cranks over fast and fine, but won't start. the second I release the key to run position it starts. It doesn't matter if it's hot or cold start. this is something that started acting up for a few weeks, about 90% of the time. nothing new, other than a new key set I installed about six months ago. I believe it's the ignition switch, but before getting one I want to here your opinions. Am I correct in my thinking????