The American-ordered drone strike that killed one of Iran’s most powerful military leaders, Qassem Soleimani, has triggered retaliation from Iran and put American troops in the Middle East on heightened alert. It has also brought foreign policy to the top of the news cycle. How events unfold from here is uncertain, but we leave that analysis to others with more expertise in world affairs. Instead, we’d like to take a step back and use political science and polling data to explore the question of how heightened tensions with Iran could affect the 2020 primary and general elections.

First, most political science research has found that foreign policy doesn’t significantly affect people’s votes. But this isn’t always the case. For example, foreign policy can have more of an impact when it’s a big part of the national conversation and when the two parties have clearly contrasting positions on it — two conditions that this Iran episode could meet.

We don’t actually know that much about the role international affairs play in primaries, though, as it’s rare for a primary candidate to be experienced in foreign policy. But this year, we have such a candidate in former Vice President Joe Biden. And two recent polls say that Democratic primary voters do trust him the most on foreign policy. According to CNN, nearly half (48 percent) of Democrats and Democratic leaners said they thought Biden could best handle foreign policy; Sen. Bernie Sanders came in second place with just 14 percent. And in a poll taken immediately after the strike that killed Soleimani, HuffPost/YouGov found that 62 percent of Democrats and Democratic leaners trust Biden on Iran, although Sanders and Sen. Elizabeth Warren weren’t too far behind, with 47 percent trusting each of them (respondents were allowed to select multiple candidates they trusted).

But even if the initial setup of the chessboard privileges Biden, how the candidates move on the issue could also be determinative. Someone like Sanders, who has been critical of Biden’s vote to go to war with Iraq, could seize the upper hand if the primary becomes a question of who is the most anti-war. Voters will likely be listening closely to what the candidates say about Iran in next week’s debate, and that could be a make-or-break moment for many of the candidates, as one theory of how foreign policy can affect primaries is that it serves as a litmus test that all serious candidates must pass.

Take the 2016 Republican primaries, when Ben Carson may have flunked such a test when, after the coordinated terrorist attacks in Paris in November 2015, he struggled to articulate how he would combat terrorism. Even his own advisers said publicly how unprepared he was on the issue. And although it’s impossible to know exactly how much this hurt Carson in voters’ eyes, he had been running even with now-President Trump in the polls at the time of the attacks, but he sharply declined thereafter and ceased to be a serious threat for the nomination.

Extreme examples aside, though, Iran’s effect on the primary might be fleeting. News cycles move on, and past events touted as “game changers” have failed to permanently change the state of the race. So remember any polling bump that Biden (or anyone else) gets this week could wear off quickly, especially if the conflict defuses.

For Iran to have any real effect on the general election, it would likely have to stay in the news for the next several months. And even then, it’s not that clear what that effect might be. In theory, you might expect Republicans to have the advantage in an election focused around national security: The GOP has long been seen as better than Democrats at protecting the country from external threats, according to Gallup polling. However, the gap has narrowed during the Trump era (as of 2019, 50 percent trusted Republicans, and 44 percent trusted Democrats), and other polls suggest Trump himself is not very well trusted on foreign policy.

It’s possible that Trump could become more popular in the wake of this month’s attacks thanks to something called the “rally-around-the-flag effect,” or the idea that major international crises can unite the country around the commander-in-chief. But it’s not an ironclad rule; context plays a major role in whether a rally-around-the-flag polling bump develops at all. Generally speaking, political scientists attribute rally-around-the-flag effects to two things: patriotism and the fact that a president’s opposition typically stops criticizing him during times of war. This episode with Iran, however, meets at best one of these two criteria: While the situation might tug at the country’s patriotic heartstrings, lack of dissent for Trump’s leadership hardly seems guaranteed. Democrats running for president and in Congress have already expressed alarm at the strike against Soleimani and questioned Trump’s decision-making process.

In addition, factors like the seriousness of the event, whether the country is already fatigued by war, the president’s approval rating before the event, and the level of media coverage of the event can all influence the size of the rally-around-the-flag effect, or even whether there is one at all. Studies have shown, for instance, that small deployments of force — basically, anything short of full-scale war — barely produce any effect. All of these factors probably combine to make a rally-around-the-flag effect unlikely in the current circumstances. And, of course, Trump’s approval rating has been remarkably stable for the last few years, despite several major news events, so our prior should probably be that one more won’t make a huge difference.

Ultimately, in keeping with our highly polarized times, the most plausible theory is probably that opinion on Iran will break down along partisan lines — and therefore won’t do much to change the trajectory of the general election. One of political science’s most consistent findings on this issue is that elite cues drive public opinion on foreign policy. In other words, if the president’s critics support a conflict and bend the metaphorical knee to the commander-in-chief, the public takes note and does the same. But if elite opinion splits along partisan lines — as it is doing so far on Iran — then so will public opinion.