Eight Democrats and two Republicans died during the 65th Congress, and initially were all replaced by appointees except in Wisconsin.

In Wisconsin, Democratic Senator Paul O. Husting died on October 21, 1917, and his seat remained vacant until an April 1918 election.

The elections converted both seats from Democratic to Republican, thus marking the first time since the popular-election of Senators was mandated by the Seventeenth Amendment three years earlier that both Senate seats in a state flipped from one party to the other in a single election cycle.

Democrat Thomas Taggart was appointed by Governor Samuel Ralston on March 20 to continue the term until a November 7, 1916, special election.

Taggart lost the special election to Republican James Eli Watson.

The incumbent, Republican Carroll S. Page successfully ran for re-election to a second full term.

[70] With the Republican Party dominant in Vermont, as it had been since its founding in the 1850s, Democratic candidate Oscar C. Miller was little more than a token opponent for Page.