Why hasn’t there been more disruption in Congress? Looking at the highly disruptive presidential primary campaign, some analysts are scratching their heads and asking that very question. In primary election after primary election, Republican congressional incumbents—such as Paul Ryan, John McCain, and Marco Rubio—triumph over their foes. Some have argued that this is a sign that Trump’s disruptive candidacy is a one-off—an angry spasm that will depart after November so that the GOP can return to business as usual.
However, the primary victories of Speaker Ryan, Senator McCain, and Senator Rubio in their respective primaries should not necessarily be taken as a major endorsement of the current ideological status quo. In part because they are often skilled politicians, incumbents are very hard to defeat in a party primary. According to statistics compiled by Greg Giroux, outside of cycles that happen right after congressional redistricting, only a handful of congressional incumbents (if even that many) are usually defeated in primary elections. Since 2000, only 6 incumbent senators have lost their party primaries. One of those incumbents was Arlen Specter, who lost the 2010 Democratic primary after abandoning the GOP in 2009, and two other of those incumbents ended up winning reelection as third-party candidates (Joe Lieberman in 2006 and Lisa Murkowski in 2010). Even as the ideological composition of a party changes drastically, the record of incumbents in primaries often presents an image of surprising serenity. When the Tea Party rocked the GOP in 2010, only four incumbents (two in the House and two in the Senate) lost their primaries. The Democratic party shifted from a position of divided support for the Iraq war to a vehemently anti-Iraq tone between 2002 and 2006 with Joe Lieberman being the only incumbent to be defeated in the primary over principally Iraq (and he ended up winning reelection in the general). For Democrats, Iraq played perhaps the most disruptive role not in congressional primaries but in the presidential primary of 2008, when Barack Obama used his opposition to the start of the Iraq war to outmaneuver Hillary Clinton and secure the nomination; it also played a role in fueling Howard Dean’s insurgent primary campaign in 2004.
