Americans today are most likely to name immigration the nation's biggest problem, but polling history suggests the alarm may have a limited shelf life.

In a Gallup survey released last week, 17 percent volunteered immigration as America's most pressing issue, narrowly topping concerns that weigh more consistently on the nation's mindset, like jobs and political leadership.

Though a small plurality, it was a sharp increase from the 5 percent who named the issue in Gallup's June poll, conducted just days before the youth migrant crisis at the border broke into the headlines and cast fresh light on the nation's troubled immigration policies.

Past polling shows a history of dramatic spikes in immigration concern, each coinciding with political flare-ups over the issue. The measure leapt beyond 15 percent twice in 2006, while Congress debated increased penalties for illegal immigration; and again to 10 percent in 2010, after Arizona passed tough anti-illegal-immigration laws.

But in each case, immigration concerns proved rather fickle; interest quickly sputtered as proposals died or other issues elbowed immigration out of the headlines.

That inconsistency might appear inherent in a survey that asks for respondents to name one issue — out of countless other possibilities — as the nation's most daunting, over-representing those that bask in a momentary media spotlight.

But Jeff Jones, managing editor of the Gallup Poll, said few issues match the polling sensitivity of immigration, which behaves more like an international crisis, such as Syria, than other domestic policy issues.

"Immigration is something that can flare up, but it typically doesn't stay in the headlines for months on end," said Jones. And like the ongoing Syrian conflict, which less than 1 percent named in Gallup's latest survey, "that doesn't mean it's getting any better, or they're finding solutions on it."

Since 2010, however (the last time immigration worries erupted in the polls), the nation's interest in an immigration overhaul had steadily increased, he said. Polls had shown a marked shift from a majority worried about "halting the flow of illegal immigrants" to instead favor "dealing with immigrants already here."

But that trend could reverse amid the current border crisis, he added. Those who named immigration America's top problem in the latest survey skewed older and more Republican — groups that typically prioritize tightening border security.

Still, with three months left before the midterms, prior surges in immigration worries would have crested long before Election Day. And according to Stella Rouse, a government professor at the University of Maryland, immigration just hasn't been the issue to drive voter choices in the past.

"If you look at polls that track voters' concerns, immigration is never at the top of the list," she said. Instead, voters tend to be driven more by issues that have a more consistent foothold in our worries, like jobs and education — a trend she emphasized extends even to Hispanic voters.

But she noted this current immigration crisis could have greater longevity, in political terms, than others. "You have the whole populace engaged in this issue; before you had pockets of it," she said, pointing to decisions about harboring young migrants being made in states around the country.

And both parties have at least one good reason keep up the combative, headline-worthy rhetoric, added Efrén Pérez, a professor of political science at Vanderbilt University: It fires up the bases.

Copyright 2016 NPR. To see more, visit http://www.npr.org/.