No appointed senator has ever won a primary runoff election, according to political historian Eric Ostermeier of the University of Minnesota.
And even elected senators have struggled in primary runoffs; only two who made it into a runoff with a second-place initial finish have gone on to win their nominations. They were Thad Cochran (R-Miss.) in 2014 and Charles Culberson (D-Texas) in 1916, according to Ostermeier.
Had Strange pulled it off, it would have been “quite a notable nomination victory,” wrote Ostermeier.
Set aside the runoff statistics and there’s a mixed bag of results for appointed senators. Two who pulled off victories were Sen. Brian Schatz (D-Hawaii) in 2014 and Sen. Michael Bennet (D-Colo.) in 2010. Both won highly competitive primaries after they were appointed.
The last appointed senator defeated in a primary was Frahm (R-Kan.) in 1996, when she lost to Sam Brownback in the race to complete the term of Republican presidential nominee Bob Dole.