Partisan risk caused by a disproportion in the number of seats up for election held by each party

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Terms and Concepts
Partisan Risk

In some sets of elections, there is a partisan risk caused by a disproportion in the number of seats up for election held by each party.

The factor matters when election analysts are thinking about sets of elections and what might happen to each party because of a set of elections.

When election analysts consider this particular partisan risk factor, they are not thinking about what might happen in a particular election. Rather, they are thinking about:

• What might happen to a given party's position of partisan dominance or majority/minority control in a particular chamber. For the purposes of this article, we refer to this as "chamber dominance".
• What might happen to a given party's position of partisan dominance across a particular type of office, such as all governors or all mayors. For the purpose of this article, we refer to this as "office dominance".

Chamber dominance is more significant when thinking about this risk factor. It matters more if one party holds majority control in a chamber (like the United States Senate or the Montana State Legislature) than if it holds a majority of all American governorships, because a position of partisan dominance in a chamber gives the party in that position significant additional rights over those of the minority party.

What is a "set of elections"?

Examples of "sets of elections" are:

• All elections for U.S. Senate held in a given year
• All elections for U.S House in a given year
• All elections for governor held in a given year
• All elections for state legislative seats held in one state in a given year or held throughout the entire country in a given year
• All elections for state attorneys general held in a given year
• All elections for school board members held in one district, or in one state, or throughout the entire country in a given year

Examples in 2018 where partisan risk mattered

Chamber dominance

• In the U.S. Senate elections of 2018, 35 United States Senate seats were up for election. Heading into November 2018, the Republican Party held majority control of the U.S. Senate with 51 Republican seats to 47 Democratic seats and 2 Independent seats. However, in the November election, of the 35 seats that were up, 26 were held by Democrats (including 10 in states that Donald Trump won in 2016) while only nine were held by Republicans. This means that the Democratic Party was in a greater position of relative risk than the Republican Party when it came to an analysis of how many of these seats would be in Democratic or Republican hands after the election. That, in turn, meant that the Republican Party stood a greater chance of keeping its majority control of the entire U.S. Senate than would be the case if the seats up for election were more evenly distributed between the parties.

Office dominance

• In the gubernatorial elections of 2018, 36 gubernatorial seats were up for grabs. Heading into the election, the Republican Party controlled 26 of the 36 seats that were up. This meant that the Republican Party was in a greater position of relative risk than was the Democratic Party, when it came to considering how many of these seats would be in Democratic or Republican hands once all the votes were counted.

Examples in 2016 where partisan risk mattered

Chamber dominance

• In the U.S. Senate elections of 2016, 34 United States Senate seats were up for election. Heading into November 2016, the Republican Party held majority control of the U.S. Senate with 54 Republican seats to 44 Democratic seats and 2 Independent seats. However, in the November election, of the 34 seats that were up, 24 were held by Republicans while only 10 were held by Democrats. This means that the Republican Party was in a greater position of relative risk than the Democratic Party when it came to an analysis of how many of these seats would be in Democratic or Republican hands after the election. That, in turn, meant that the Republican Party stood a greater risk of losing its majority control of the entire U.S. Senate than would be the case if the seats up for election were evenly distributed between the parties (i.e., if of the 34 seats are for election, 17 were held by Republican and 17 were held by Democrats).

Office dominance

• In the gubernatorial elections of 2016, twelve gubernatorial seats were up for grabs. Heading into the election, the Democratic Party controlled eight of the twelve seats that were up for election. This meant that the Democratic Party was in a greater position of relative risk than was the Republican Party, when it came to considering how many of these seats would be in Democratic or Republican hands once all the votes were counted.

• In 2016's municipal elections, in the country's 100 largest cities, 25 mayorships were up for election. Of the mayors who were serving in those mayorships at the time of the election, 13 were Republican, 11 were Democratic and one was nonpartisan. These positions accounted for 48.1 percent of all Republican mayors, 16.4 percent of Democratic mayors and 33.3 percent of nonpartisan mayors in the 100 largest cities at this time. This large percentage of seats up meant that Republicans were on the defensive this year. San Diego's Kevin Faulconer, the only Republican mayor in the country's 10 largest cities, ran for and won re-election.