1994 Chevy Silverado Wont Start

Electrical problem
1994 Chevy Silverado V6 Two Wheel Drive Automatic 220000 miles

The ignition switch will turn to the on position and to the lock and ACC positions, however it will not turn to the start position. What is stopping it from going all the way? It was getting hard to move before this and the all of a sudden it wouldnt go any farther just today.