I have located the problem. There is a plug-in connector to the clutch safety switch. This connection did not "snap" into place, nor provide a snug fit. I could very easily slide the connection apart. When I held it snug, the mower started immediately. I used a plastic toothpick to slide between the plug and the safety switch to create a snug connection. The mower starts perfectly.
Any idea how to make this connection snug in a more permanent or professional way?