President Obama visited the Pentagon on Monday in a rare visit intended to update him on operations against the Islamic State. Afterward, he warned that the effort to defeat the extremists would "not be quick."

The visit comes as the Islamic State -- also referred to as ISIS or ISIL -- has been a relatively back-burner political issue. Republicans and Democrats have largely united behind the current air strikes campaign, and early polling showed large bipartisan agreement that more force might be necessary -- even as the Obama administration continues resist even the idea of ground troops engaging in combat.

But that could soon change. As the 2016 campaign really gets moving, it appears there will be significant pressure on -- or at least incentive for -- GOP candidates to up the ante when it comes to fighting the Islamic State. Similarly, there could be similar pressure on Democrats to go dovish.

Case in point: a new poll of likely 2016 Iowa caucus-goers.

The poll shows nearly three-quarters (72 percent) of those likely to determine who wins the first state in the GOP presidential nominating process would like for the United States to send ground troops to fight the Islamic State. And perhaps more resoundingly, about half of all likely GOP caucus-goers (51 percent) say they "strongly" support this position.

On the other side, just 29 percent of Democrats support ground troops, and about half (52 percent) say they feel strongly that the United States should not send them.

Those are massive chunks of the electorate in an important early state that say this is an issue that is very important to them. And it's hard to believe the candidates won't try and appeal to those groups.

What's particularly interesting about this issue is that the partisan gap generally hasn't been so wide. In fact, a March Quinnipiac poll showed 73 percent of Republicans and 53 percent of Democrats agreed on sending ground troops. (That poll, notably, was conducted a couple weeks after video surfaced of the Islamic State beheading 21 Egyptian Coptic Christirans on a beach.) A CBS/NYT poll later that month showed 62 percent of Republicans and 38 percent of Democrats in support.

The new poll showed a much-larger gap between the two parties -- likely in part because the caucus process tends to be dominated by more passionate and polarized voters.

But whether Iowa is representative of the rest of the country isn't the question; it's role in the process is clear, and the people there seem to feel strongly about fighting the Islamic State -- or not.

When foreign policy becomes a major issue in the 2016 primary process, remember this poll.