Polls, Politics, and the 2021 Virginia and New Jersey Elections

The pendulum versus policy explanation, and how they differ in their implications.

Robert E. Erikson
Andrew Gelman
Robert Y. Shapiro
November 05, 2021

Two notable things happened in the recent 2021 elections. First, there was a Republican swing in New Jersey, Virginia, and elsewhere. Second, the polls were off in New Jersey, with the Democrat receiving only about 51% of the two-party vote, after being at about 54% in the polls. A three percentage point polling error is hardly unprecedented, but it's on the high end of what pollsters like to see.

As students of political science and statistics, we would emphasize two aspects of the 2021 Virginia and New Jersey governor elections. They both have to do with the surprise—given what was expected in pre-election polling—at how well Republicans did, especially in New Jersey, and raise the question: How much can we count on the polls to provide an accurate baseline?  

In 2016 and 2020, the presidential election polls revealed problems in underestimating the Republican vote in key states, as described in an important report by the American Association for Public Opinion Research. But for Virginia and New Jersey, the 2020 pre-election Real Clear Politics polling averages for president were within two percentage points of the actual results. Further, the average for the 2017 governor election polls in New Jersey was within one percentage point for Democrat Phil Murphy’s victory. In the 2017 Virginia election, the polling average underestimated Democrat Ralph Northam’s victory by five points—an underestimate of the Democrat, not the Republican.

How the New Jersey Polls Differed From Virginia

How did the Virginia and New Jersey polls do in 2021?  There were not many of them, but based on the Real Clear Politics polling average, the Virginia polling was on target: the poll average and the final results both had Republican Glenn Youngkin winning by two points.

New Jersey was different. There were similarly few polls in the week before the election, and they were substantially off the mark.

Polling errors are of interest to journalists, political junkies, and polling professionals.  A national partisan swing—also reflected in the president's dropping approval rating—is important to just about everybody, given the sharp differences between the two parties in issues ranging from unemployment benefits and corporate taxes to energy and environmental policy to immigration, abortion, and policing.

While the New Jersey polling was a surprise, the overall election result was less so to us. And we say this without discussing what the pundits have lamented over for the Democrats: that the Biden administration’s problems hurt Democratic candidates and the hair-pulling over campaign issues had an impact on elections in Virginia and New Jersey. Based on historical trends, the party that has just won the White House almost never wins the New Jersey or Virginia governorship the following year. All presidents—Democrats and Republicans, popular and less so—have faced this deflation of their party’s support. The question is why.

Centrist Voters and Ideological Balance

Some claim that centrist voters tend to seek an ideological balance of their government officials. American politics is polarized, but some swing voters remain. The Democrats currently control two of the three branches of the national government (Congress and the presidency), and it makes sense that swing voters will want to balance that by voting Republican in the election that immediately follows. Some identify the reason to be that voters for the losing side in the presidential race are more motivated to vote in subsequent elections. These same forces are likely to continue in the 2022 midterm elections. Historically, the president’s party almost always loses seats in the midterm election.

The swinging pendulum explains the vote but not Biden's declining approval ratings, which we can attribute to bad news from Afghanistan, the continuing disruption caused by Covid, and a sluggish economy. But most presidents have seen a decline in approval during their first year in office.

The swinging pendulum explains the vote but not Biden's declining approval ratings. But most presidents have seen a decline in approval during their first year in office.

A second set of explanations for the election loss are more specific to the actions of Biden and others in the Democratic party. From the left, the argument is that voters are slamming the Democrats for being ineffectual and not delivering on their campaign promise of economic relief. From the right, the argument is that, now with Trump out of the way, moderate voters can see leftism in all its glory—and they don't like it.

One way to sharpen this distinction is to imagine what would have happened had Biden led his party to enacting a large spending bill a few months ago as originally planned. On the one hand, this would have represented an argument in favor of the Democrats as a party that gets things done. On the other, this could have served as motivation for the pendulum to swing back—even if each of the items on the bill were broadly popular. Indeed, had a big bill passed, this could be blamed for the recent mediocre economic news. Looking back, perhaps had Biden passed a truly centrist bill with Republican support, this could have helped the Democrats in the election. The president is looking toward 2024, and a stimulus that begins now could lead to the economy springing back in the next three years. Political science research suggests that economic trends during the election year can determine the winner.

Were We Too Influenced by the Georgia Runoff in January?

The two explanations—pendulum and policy—can be fit together, but they differ in their implications. Given our political science background, we are inclined to go with the pendulum theory, but in that case why was the political science profession not telling everyone to expect a Republican swing in 2021? It may be that we were too influenced by the Georgia runoff elections in January, which were won by two Democrats: a counterexample to the usual expectation of a swing away from the party in power and perhaps explainable by continuing anger at Trump's refusal to accept the November election outcome. 

If we look back at 2020, we can see that the GOP held its own apart from Trump’s defeat. The 2020 election results foreshadowed the 2021 Republican gains. While Trump was losing the presidency in 2020, the Republicans still picked up 13 seats in the House of Representatives and maintained their control of 30 state legislatures compared to the Democrats’ 18.

Without Trump on the ticket, the Republicans may find themselves better off. The Democrats will be confronted by this challenge in the 2022 midterm elections, which will be a referendum on the performance of the Biden administration and the Democrats in control of Congress, especially regarding the Covid-19 pandemic and the national economy.

Robert E. EriksonAndrew Gelman, and Robert Y. Shapiro are with the Department of Political Science at Columbia University. Professor Gelman has a joint appointment with the Statistics Department, and Professor Shapiro is also with Columbia's School of International and Public Affairs.

This column is editorially independent of Columbia News.