Foreign affairs rarely capture the attention of Americans except in broad circumstances — such as when a war is on, hot or cold — but voters appear to be especially underweighting the topic in the context of next year's election.

In a recent poll of likely Democratic primary or caucus voters, by the research firm Ipsos for the data-driven website FiveThirtyEight, the topic wasn't even among the top 10 issues that mattered most to respondents. That finding mirrors tendencies in polls of the broader electorate.

In the FiveThirtyEight/Ipsos poll, just 2.9% of respondents listed foreign affairs as the issue most likely to affect their vote. Topping the list was health care, at 19.2%. Jobs (12.9%), climate change (12.3%) and immigration (4.9%) fared better than global concerns.

Yet global relationships matter very much to several of those higher-ranking concerns.

In its most basic formulation, foreign policy involves military and diplomatic engagement for advantage in territory and resources, either proactively or in response to aggression against one's country or that of an ally. Such action can have both strategic and humanitarian goals.

Thereafter, trade policy — the negotiated, peaceful exchange of goods and resources — is perhaps the overarching concern. At stake are prosperity and jobs.

Under President Donald Trump, the U.S. has pulled out of multilateral trade agreements and has sought either to renegotiate them or to negotiate new deals bilaterally, using tariffs as pressure. Trump believes the strategy can produce a stronger American economy, though this is at odds with the long-since-made case that freer trade lifts all boats globally. The problem, to Trump's political advantage, is that the benefits of free trade are broadly distributed and accrue over decades, while costs are concentrated and felt in real time.

For similar economic motivations, Trump pulled America out of the Paris Agreement on climate change mitigation. Experts argue that the climate threat must be addressed with global cooperation. But the rub, again, is deciding what sacrifices must be made by whom for the longer-term security of the planet and its population.

Climate change, in turn, promises to distort immigration as strains on resources lead to instability and an increased flow of refugees. The U.S. military has long planned for engagement brought on by such developments.

All of which raise the most important consideration of all with regard to the presidential campaign. Whatever domestic goals any new administration might have, job one will be to restore America's credibility in the world following the tenure of a president who, whatever his motivations, has performed with a style that has diminished global faith in our country.

Yet there is division among the Democratic candidates about U.S. engagement, as detailed in a commentary written by Doyle McManus of the Los Angeles Times and republished by the Star Tribune. All of the candidates appear to favor a decrease in military engagement, and nearly all can be assumed to bring a more diplomatic approach to the job. But there's a real strain of isolationism in some.

Meanwhile, voters' thoughts on foreign policy may be more sophisticated than their apparent disinterest in the topic indicates. According to a survey this year by the Chicago Council on Global Affairs, 69% think the U.S. is better off playing an active role globally, 5 percentage points higher than in 2016 and nearly as high as after 9/11. Eighty-seven percent think international trade is good for the U.S. economy. Seventy-four percent think military alliances make the country safer, though just 27% think military interventions do.

And the Center for American Progress, analyzing the results of a survey of its own this year, writes: "The findings suggest that American voters are not isolationist. Rather, voters are more accurately described as supporting 'restrained engagement' in international affairs — a strategy that favors diplomatic, political, and economic actions over military action when advancing U.S. interests in the world."