In recent months wily old (66) Socialist Pietro Nenni, the he-loves-me-he-loves-me-not Stalin Peace Prizewinner, has furnished Italian politics with more suspense scenes than a Pearl White serial.

Teetering on a one-vote majority in the Chamber of Deputies, Italy’s Christian Democratic Premier Amintore Fanfani has often cast longing eyes toward the 84 left-wing Socialist seats controlled ...