Lisa's teacher, Miss Hoover, comes down with Lyme Disease and a substitute teacher, Mr. Bergstrom, takes over the class. Bart's class, meanwhile, prepares to elect a president. Mrs. Krabappel nominates Martin Prince. Sherri and Terri nominate Bart. During a Presidential debate with Martin, Bart tells jokes and wins the class's support. Meanwhile, Lisa develops a crush on Mr. Bergstrom.

Lisa runs into Mr. Bergstrom at a museum and is embarassed when Homer displays his usual oafishness. Sensing that Lisa is missing something in her relationship with her dad, Mr. Bergstrom takes Homer aside to suggest he be a more positive role model. At school on Monday, Lisa is shattered to find Miss Hoover is back and Mr. Bergstrom is gone. Certain of Bart's inevitable victory, none of the kids in his class vote except for Martin and his friend, Wendell. Mrs. Krabappel joyously announces Martin as the class president.

Devastated by Mr. Bergstrom's departure, Lisa takes her grief out on Homer, calling him a baboon. With Lisa grief-stricken and Bart reeling from his election loss, Homer decides it is time to act like a father. After he gives Lisa a pep talk, she apologizes. Next, he pays Bart a visit. Pointing out that being class president is a nonpaying job and requires doing extra work, Homer makes Bart glad that he lost the election. Although it is still early, he asks Marge if they can go to bed, saying that he is on the biggest roll of his life.