U.S. presidential elections rarely turn on voters’ views on foreign policy. Domestic issues such as the economy and health care, including the coronavirus pandemic this year, are almost always seen as more important by voters.

But foreign policy can turn on the outcome of elections. And that is especially true this year, when not only the major party candidates but their partisan supporters offer starkly different visions for America’s role in the world.

The foreign policy differences between President Donald Trump and former Vice President Joe Biden are well known. Trump offers an “America First” vision that rejects “globalism” in favor of unabashed nationalism. Biden, in contrast, favors a more internationalist approach that emphasizes cooperation with other nations and international institutions.

Yet, what is striking is not that the two candidates offer different perspectives on how America engages the world, but the fact that their respective voters increasingly share those very distinct perspectives. As a new Chicago Council survey on public attitudes on foreign policy shows, never before have Americans been so divided on these issues.

The difference between Democrats and Republicans on foreign policy can be seen across a whole host of issues, starting with their views on the coronavirus pandemic. Whereas 80% of Democrats think that the pandemic has made it more important for the United States to coordinate and collaborate with others to solve global issues, 58% of Republicans believe it is more important to be self-sufficient as a nation and not depend on others.

More generally, twice as many Democrats as Republicans (72% to 36%) believe that “problems like climate change and pandemics are so big that no country can solve them alone, and international cooperation is the only way we can make progress in solving these problems.”

Democrats accordingly favor internationalist approaches, including increasing U.S. participation in international organizations (63%), providing humanitarian aid (59%) and negotiating international agreements (55%). They also believe that international organizations such as the World Health Organization (71%), the United Nations (68%) and the World Trade Organization (53%) should be more involved in solving global problems.

By contrast, nearly half of Republicans (48%) believe the United States is “rich and powerful enough to go it alone.” Their preference is to emphasize unilateral capabilities, such as increasing the use of drone strikes (44%), imposing sanctions on other countries (43%) and placing tariffs on goods traded with other nations (43%). And when it comes to international organizations, few Republicans favor increasing their involvement in solving global problems; and a third believe organizations such as the U.N. (34%), WHO (39%) and WTO (30%) should be less involved.

These different approaches to foreign policy reflect deep-seated differences about the critical threats facing the United States today. Importantly, there is no overlap between the top five threats listed by Democrats and Republicans.

Democrats are worried about global problems such as the pandemic (which 87% see as a critical threat) and climate change (75%), followed by societal issues such as racial (73%) and economic inequality (67%). Seven in 10 Democrats (69%) are also concerned about foreign interference in U.S. elections.

None of these is among the top five threats identified by Republicans. Instead, they identify traditional security challenges as the most critical threats facing the country, including the development of China as a world power (67%), international terrorism (62%) and Iran’s nuclear program (54%). Six in 10 also consider large numbers of immigrants and refugees coming into the country (61%) — a long-standing Republican concern — and domestic violent extremism as critical threats.

The partisan differences are perhaps most starkly present on the one foreign policy issue that has penetrated the election campaign — U.S. relations with China. While views of China among all Americans has plummeted to their lowest level since diplomatic relations were established in 1978, there are still big differences on the degree to which China poses a threat and how the United States should deal with it.

Two-thirds of Republicans see China’s development as a world power as the biggest critical threat facing the United States today. Yet, while a plurality of Democrats (47%) agrees that China is a threat, they rank it just 13th on the list of 15 critical threats. And while a large majority of Republicans (64%) say the United States should actively work to limit the growth of China’s power, a similar majority of Democrats (60%) instead favor friendly cooperation and engagement with China.

It’s been a while since American politics stopped at the water’s edge. Political polarization has increasingly divided Democrats and Republicans across the board, including on foreign policy. But the partisan differences this year on foreign policy are wider and deeper than ever, as are the fundamental choices offered by the two leading candidates.

This, then, may well turn out to be the most consequential foreign policy election in many decades — even if most of the voters fill in their ballots with very different concerns in mind.

Ivo Daalder is president of the Chicago Council on Global Affairs and a former U.S. ambassador to NATO.