1993 Ford Tempo cranking

Car started not wanting to crank unless you played with the automatic floor shifter. With it in park, wiggle the shifter a little and it would finally turn over. It has gotten to where this doesn't work as well as it first did. Now I have to hold the key over as to crank it, while at the same time moving the shifter to neutral. While leaving park with the shifter, as soon as it hits neutral it cranks and runs great. I've been told its the tranny. And i've been told its just a saftey switch, which makes more sense to me. HELP! If it is a switch, where would it be located. Thanks for any help and info you can provide.