Ignition switch does not engage at time

When I crank the car it cranks right up most of the time. Some time the switch does not engage and there is no cranking or sound as if the switch is not engaging. When I try to start it at the relay switch are the starter it turns over but want crank and I have the key in the crank position. Then other time I turn the switch and it engage an cranks right up. Is my switch bad or could it be something else.