Sure it could be the ignition switch or the associated wiring. You're probably gonna have to start looking at the wires. You might find a wire that's shorted without too much work.
Here's something I found a few years ago.
CaradioDoc wrote:
A simple trick to finding a short is to replace the blown fuse with a pair of spade terminals, then use small jumper wires to connect them to a twelve volt light bulb. A brake light bulb works well. When the circuit is live and the short is present, the bulb will be full brightness and hot so be sure it is not laying on the carpet or against a plastic door panel. Now you can unplug electrical connectors and move things around to see what makes the short go away. When it does, the bulb will get dim or go out.
I actually just use a tail light socket from the junkyard and extended the wires. Then stripped the ends, flattened them and soldered them so I can seat them in the fuse block. Just gotta be careful they don't touch. If it's shorted it'll light up, now you can move the wires for the ignition switch around and see if the light goes out.