Many political observers see the Democratic presidential candidates as veering to the left. As veteran political journalist Thomas Edsall writes, “Leading Democratic candidates are supporting bold progressive policy initiatives.” Even the supposedly moderate Joe Biden is proposing policies that are more liberal than Hillary Clinton’s, according to a recent study. One big question is whether this shift mirrors real changes in the party’s base, or whether the candidates are becoming out of step with the party’s voters. So which is it?

One standard answer comes from how Democrats identify themselves ideologically. There, the data is clear: Many more call themselves liberal and fewer call themselves conservative. In the General Social Survey, the percentage calling themselves liberal has increased dramatically, with a sharp spike in recent years. As of 2018, more than half of Democrats called themselves liberal.

But does calling themselves “liberal” actually mean they’re liberal? A lot of political science research has concluded that most Americans do not think in ideological terms. On the other hand, as Democratic and Republican elected officials have polarized along ideological lines, it seems possible that ordinary people are now thinking about politics differently.

How I did my research

One way to assess this is to see how Americans talk about the Democratic and Republican parties and their presidential candidates. In the long-running American National Election Studies surveys, respondents are asked open-ended questions regarding their likes and dislikes about each major party and its presidential candidate. Respondents can express themselves in their own words.

My new research examines the responses collected in the 2008, 2012 and 2016 American National Election Studies, adding to similar assessments done in 1980-88 and again in 2000. Having read all of the responses for more than 3,400 respondents, I’ve gauged how many respondents talk about the parties and candidates in terms that reflect ideology or multiple policy concerns.

To be sure, many respondents don’t talk in those terms. They might describe the candidates in highly personal terms, as when a respondent who supported Clinton said that President Trump is “a maniacal moron” or a Trump supporter said that Clinton “is possibly the most corrupt and evil person to ever run for high office in the U.S.”

But others did cite ideology or policy. For example, some respondents said they liked the Democratic Party for these reasons:

  • “They have a more progressive vision for our country; more inclusive.”
  • “I like their social policies and liberal policies on social issues.”
  • “I like the health-care reform, the equal rights for women and for the gay community. I like marriage equality.”

And some ideologically minded respondents said they liked the Republican Party for these reasons:

  • “Smaller government; less intrusion on small business; civil liberties/gun rights.”
  • “Conservative judges and conservative economic plans.”
  • “Believe in free markets and limited government.”

An increasing number of Democrats talk about ideology or policy when they talk about politics

Traditionally, Republicans have been more likely to think in ideological and/or policy terms than Democrats, but my analysis shows that this is changing.

The figure below shows the percentage of Republicans and Democrats who spoke about the parties and/or candidates in this fashion. This means that respondents either mentioned at least three separate policy issues or described a party or candidate with an appropriate ideological label or concept (so the Democratic Party with “liberal,” “progressive,” etc. and the GOP with “conservative” or “for limited government” or something similar).

In 2016, 41 percent of Democratic voters mentioned ideology and/or several policies, a larger share than in any of the earlier years when a similar analysis was done. The trend among Republican voters was the opposite: A smaller fraction mentioned ideology or several policy concerns in 2016 compared to 2012.

The concern with ideology and policy is even more apparent in the Democrats’ activist base. Among Democratic voters in 2016 who participated in the campaign, such as by working for a candidate, attending a rally, or contributing money to a campaign, 57 percent cited ideology or policies.

What elicited these changes in 2016? One possibility is the insurgent campaigns of Trump on the right and Bernie Sanders on the left. Trump represented a far less ideological figure than other recent Republican nominees. As a novice politician who had supported some Democrats in the past, Trump was driven less by ideology than by identity politics.

On the Democratic side, the progressive movement represented by Sanders led some Democrats away from their usual group-based way of thinking and more toward ideological and policy concerns. Far more than most Democratic presidential contenders, Sanders openly discussed ideological concepts, proudly promoting progressivism and democratic socialism.

Democratic candidates are trying to woo Democratic primary voters

The implication for the Democratic presidential primary is clear. Regardless of why rank-and-file Democrats, and especially activists, have come to talk about politics in this more ideological fashion, Democratic presidential contenders need to woo these activists. Thus, it’s no wonder that many of the Democratic contenders are speaking about progressivism and wonky policy proposals. It is what more and more Democratic voters apparently want to hear.

Martin Wattenberg is professor of political science at the University of California at Irvine and author of “Is Voting for Young People?” (Routledge, 2016).