It’s the political scientist’s often-asked chicken and egg: does a person’s political party or policy attitudes come first?

With party and ideology so closely intertwined, the question has in the past been nearly impossible to pin down, but BYU political science professors Michael Barber and Jeremy C. Pope found a way. The duo published a study in top-ranked American Political Science Review showing that people’s policy positions are quite malleable when told that leaders of their political party support a different position.

The key to answering their question? The election of a president who has made statements both opposing and supporting a range of controversial issues.

“With President Trump as a bit of a weathervane on certain issues, it makes it easier to discern party loyalists from policy loyalists,” Pope said.

In their research, Pope and Barber studied two different groups: party loyalists and policy loyalists. Party loyalists are those who, when informed of the party leaders’ position, willingly and quickly change their policy position to align with the party leader. Policy loyalists are those who hold to their original policy preference, despite opinions or stances of party leaders that might contradict their beliefs.

“It’s odd to think about partisanship and ideology as being disconnected,” said Barber. “Why else does a political party exist rather than to advance a particular set of policies?”

Using a representative survey of 1,300 Americans, the researchers randomly assigned respondents into control, liberal and conservative groups and asked participants about their political positions on a variety of contemporary issues. The issues they explored were ones on which Donald Trump took different positions during his presidential campaign, including abortion, immigration, guns, health care, climate change and minimum wage.

Control-group participants were asked about their opinions on issues, with no mention of Trump’s position. But Barber and Pope presented participants in the liberal group with questions such as, “Donald Trump has said that he supports increasing the minimum wage over $10. How about you? Do you support or oppose increasing the minimum wage to over $10 an hour?”

In this way, the researchers could uncover the effect of a party leader’s endorsement of a policy in both a liberal and conservative direction. President Trump is unique in that most party leaders don’t endorse policies that run counter to the dominant ideology of the party, let alone advocate for both ideological sides of an issue.

Pope and Barber found that many people in each treatment group moved to support the policy when informed that President Trump likewise supported the policy. This was true of both liberal and conservative policies. “When informed of the president’s issue position, many people willingly followed that position in either a liberal or a conservative direction,” Pope said.

Respondents who knew less about politics, those who approved of President Trump, strong Republicans and self-identified conservatives were the groups most likely to be moved by seeing an endorsement of a policy by President Trump. Surprisingly, this was true of both a liberal and conservative endorsement. In other words, despite identifying as conservative Republicans, these individuals were more likely to endorse a liberal policy when told that President Trump supported that policy.

This kind of loyal partisanship should worry political observers, said Pope and Barber. They both maintain that politics are better when they revolve around more than just the party label.

“It should be about ideas and not about winning or beating the other side,” Barber said. “Politics should be about pushing ideas and policies that you think will better the country.”