This post has been updated.

As President Obama prepares to deliver a primetime speech tonight on the U.S. plan to destroy the Islamic State, it's important to remember one basic fact: Voters don't really care about foreign policy.

Just more than in one in five (22 percent) said international issues like "Iraq, Russia and terrorism" were more important to their vote in November as compared to roughly two thirds (64 percent) who said domestic issues like the "economy, health care and immigration" mattered more to them.

Those numbers are all the more revealing given that they come in a period where international affairs -- from fighting in Gaza to Russian's incursions into Ukraine to the Islamic State's atrocities -- has been front and center in the national consciousness. It's difficult to remember a time, in fact, when the foreign policy -- and, specifically, the debate over what role the U.S. is and should be playing in the world -- has been more prominent. And yet, foreign policy simply doesn't move the needle.

There are a few reasons/theories why.

1. It's is a truism of American politics that when the economy is struggling -- or perceived to be struggling -- the public cares almost exclusively about what politicians are doing to make it better. ("It's the economy, stupid.")  And, that's where we find ourselves right now.  In a Post-ABC poll released earlier this week, 63 percent described the economic recovery as weak, and even higher numbers in both the Post-ABC and NBC-WSJ poll believe the country is off on the wrong track.

2. The further we get from the Sept. 11 terrorist attacks -- the 13th anniversary of which is tomorrow -- the less focused on anything other than our country people get.  When NBC-WSJ asked a similar "international issues vs. domestic issues" question in 2006, 43 percent said domestic issues mattered more while 28 percent said international issues -- a far more equitable split than the latest findings. It is worth noting, however, that the numbers related to worries about a terrorist attack are very much on the rise. A year ago 28 percent said that the country was less safe than before September 11; that number soared to 47 percent in the new NBC-WSJ survey.

3. There is a growing sentiment in the electorate for a less muscular/active foreign policy. Four in ten voters said the U.S. should be less active in world affairs while 29 percent said they preferred the status quo and 27 percent said the country should be more active. While the "less active" number is down from 47 percent in April -- a dip likely due to the high-profile murders carried out by the Islamic State -- there remains a considerable group of people who want to spend less time looking outside of our borders.

Whatever the reasons, it's important to remember amid the scads of media coverage of the run-up to President Obama's speech tonight that a large majority of Americans are simply not all that interested.  And won't be -- no matter what he announces.

Update, 11:30 pm

Public Opinion Strategies partner Bill McInturff, who conducts the NBC-WSJ poll along with a Democratic partner, emailed to take issue with my characterization of the poll data.  He wrote:  "It’s a forced choice question. It doesn’t mean voters don’t care about foreign policy, it only means they care about domestic issues more when forced to choose. On a recent proprietary survey we just completed, when asked to rate each issue separately, concern about 'national security and terrorism' tied on the top of the list with 'economy and jobs,' which represents a significant increase in concern about security and terrorism issues since the two beheadings.