This really interesting article is by Dr. Eric Ostermeier in Smart Politics, University of Minnesota. Here is an excerpt:

North Carolina has seen incumbents lose 16 primary or general elections followed by Delaware and Illinois with 14, Missouri with 13, and Ohio and South Dakota with 12 each.

Only nine U.S. Senators have lost their party’s nomination since 1982 (with Joe Lieberman and Lisa Murkowski still prevailing in the 2006 and 2010 general elections respectively), but with each major party becoming ideologically more extreme that potentiality lurks around the corner in 2022.

And so while each U.S. Senator running for reelection may be at least slightly favored to retain their seat at this point in the election cycle, rest assured at least one vulnerable incumbent (or perhaps one currently off the board) will fall next November.

Read the full article here.