Before the general election this past Tuesday, there were 3 incumbent Senators who were ousted in the primaries: Arlen Specter of Pennsylvania, Robert Bennet of Utah, and Lisa Murkowski of Alaska. In the general election, 2 more incumbent Senators lost, but the total sum of ousted incumbents is only 4, due to a unique quirk. While the Democratic incumbent Senator of Wisconsin Russ Feingold and the Democratic incumbent Senator of Arkansas Blanche Lincoln both lost on Tuesday, thereby adding 2 to the tally of ousted incumbents, Lisa Murkowski revived herself from the beaten incumbents with a last-minute write-in campaign. As a result, the total amount of ousted incumbent Senators in 2010 is 4.
Among the past 20 elections, including midterm and general election cycles back to 1970, there have been ousted incumbent Senators in every one of these elections, according to the University of Virginia Center for Politics. The median number of losing incumbent Senators is 4. The election cycle with the most ousted incumbent Senators is 1980, when 9 incumbent Senators lost. Also, Democrats had not lost any incumbent Senators in either 2006 or 2008, but the losses of Specter, Feingold, and Lincoln ended this streak.
Lastly, with the addition of the 2010 data to the past 20 elections, the median number of losing incumbent Senators is reinforced at 4. Contrarily, the typical turnover in the House of Representatives was exceedingly above average in 2010.