The big news Monday in the political world was that Rep. Michele Bachmann has surged to the lead in a new Republican poll in Iowa.

The even bigger news is that Bachmann’s lead over former Massachusetts governor Mitt Romney may be significantly wider than the four percent margin reflected in the poll, and we may in fact be under-selling her surge in the Hawkeye State

A closer look at the Voter/Consumer Research poll shows that among voters who are described as the “most attentive,” Bachmann leads by a much-wider 14-point margin, 32 percent to 18 percent.

Those numbers matter for several reasons.

One, of course, is that attentive voters are more likely to turn out to vote. And that’s especially true in Iowa, which uses a caucus system dominated by — you guessed it — more attentive voters. These kinds of voters are much more likely to be willing to trudge through the snow on a Thursday night in the dead of winter to cast their votes.

But the more important reason is the enthusiasm gap in the GOP presidential field. Put plainly, Bachmann is the candidate that evokes passion in Republican voters at the moment. Her opponents, by and large, don’t. And that gap means her lead could very well grow.

“What it means is the news stories are probably not over-estimating her current fact, they may be under-estimating it,” said GOP consultant Dan Hazelwood. “And second, she has a sizable base to mobilize for a caucus event.”

Added Democratic pollster Fred Yang: “She’s clearly got a constituency — the aware and the hard-core — which is a positive sign for a primary.”

We wrote last month about the disillusionment among even many Republicans with the GOP presidential field, and the new polling results in Iowa only reinforce that.

Bachmann has emerged as a candidate to get excited about in a field of candidates where there aren’t many candidates that are all that alluring to Republican voters.

Aside from Bachmann, the only other 2012 candidate who scores better among “more attentive” voters than regular voters is businessman Herman Cain, who gets a bump from 9 percent to 12 percent in the Iowa GOP poll.

Cain, like Bachmann, is something different from the standard-issue Republican presidential candidate, and voters seem to be yearning to support someone different right now.

Both remain somewhat unknown to many people. But the fact that the people who do pay attention like Bachmann and Cain spells good things for their campaigns as more and more Republicans tune into the presidential race

“An early lead among this population means she can continue the momentum,” said GOP pollster Tyler Harber of Bachmann.

While the “more attentive” description is tough to quantify, it’s along the same lines as the difference between polls of registered voters and likely voters. The registered voter pool will often include more casual voters who may or may not actually show up on election day. The likely voters pool gives you a better idea of who is leading, especially in a low-turnout race.

When we get closer to election and the likely electorate begins to take shape, pollsters will tend to test likely voters; further out, they test registered voters to get a bigger picture.

A poll of “more attentive” voters can give a better picture of which way the race is headed, because the electorate generally starts to learn more about the candidates as Election Day nears. It’s also a good indicator of who is more likely to turn out – particularly in an election where turnout is lower than normal.

For Republicans, they may very well be facing a low-turnout race unless the presidential field starts inspiring more voters.

And just like in 2010, the more active and excited Republican voters could very well be the ones voting for the more conservative, tea party candidates like Bachmann.

At the same time, a Republican presidential primary does feature higher turnout than your normal primary. And the turnout in 2012 won’t be as low as in a midterm election year like 2010.

Given the apparent lack of effort from the Romney campaign in Iowa and the lack of another frontrunner, though, right now it’s very much Bachmann’s race to lose.

Romney and other more establishment candidates have plenty of time to excite the Republican base, but it’s pretty clear for now that there is a significant enthusiasm gap in the Republican presidential field. And we could see some pretty significant shifts in the race because of it – not just in Iowa, but in other primary and caucus states as well.