How does the author use foreshadowing in Out to Canaan?

In Chapter Nineteen, the mayoral election has been something of a subplot throughout the novel that has suddenly become the main focus of the novel. Father Tim has backed Esther Cunningham from the beginning, as did most of the town for the better part of the campaign. Father Tim also is the only one who knows where Mack is getting all his money, but has elected as a man of the cloth to keep his mouth shut. In the end, it seems that this has backfired and Mack has won the election. This news leaves the reader speechless, imagining Edith Mallory taking control of the town council through Mack. This foreshadows a dark time for Mitford.