What is the significance of US Foreign Policy during US Presidential elections?

US Presidential candidates talk a lot, about a lot of things. Foreign Policy is a historic talking point for Democratic and Republican candidates alike, for separate reasons. Pundits argue that Foreign Policy might be irrelevant in comparison to other factors that historically have been proven to carry more sway, such as perceived competence, 'like-ability', and domestic economic affairs. However, even if these factors are assumed to be the most important, Foreign Policy positions play a key role in shaping voter perceptions of candidates and therefore is influential in candidate selection. This rational is illuminated when considering key factors that affect voter behavior and how foreign policy can affect these.
Two key theories of voter behavior are those of 'Retrospective voting' and 'Sociological voting'. The Retrospective voter theory claims that when deciding which party to vote for, voters will ask themselves, "Am I better off now, than I was before?" Based on the information available to the individual in that moment, they will make a rational choice on whether or not to stick with the same candidate or party as before. Often this can be tied to "pocket book" voting, otherwise saying people care most about whether or not the economy is stable and their individual financial status is sound. If not, they might punish the incumbent party or candidate by not selecting them. However, recent social movements such as those around"Black Lives Matter" and environmental sustainability, prove that the question of "am I better off now?" can also consider non economic factors such as civil rights, individual safety, and safety from natural disasters. The argument that factors beyond immediate, individual welfare also affect voters' choices aligns with the theory of sociological voting. This theory maintains that how people vote is influenced by the groups and cultures with which they are affiliated. For example, someone who comes from a historically rural town in Texas that has always voted for Republicans, cares deeply about anti-abortion and send many young people to the military with pride, will be influenced through their ingrained values to vote for the Republican party. In both theories, Foreign Policy positions can still have an influential role.
Evaluations of wellbeing by individuals and cultural subsets can be influenced by foreign policy, when these decisions affect domestic affairs. Foreign developments such as decisions to exit trade deals or activate major trade restrictions affect everyday Americans and their ability to do business and provide for their families. Military actions are the most striking example - overseas engagements and domestic terror attacks affect the mood of the public and influence whether they're looking for a tough leader or a cool-headed diplomat. Candidates' foreign policy stances are a shortcut for voters to make a judgment on how a candidate would be likely to respond in a crisis, and what their general character is in terms of being risk averse, pro-military, or isolationist.