In this Tuesday, Aug. 3, 2010, file photo, the sun shines behind a voting sign outside a polling location in Lawrence, Kan. (AP Photo/Orlin Wagner)

The fact that Democratic voters are less enthusiastic about the 2014 election isn't news. We've known for a while that the so-called Obama Coalition isn't exactly conducive to winning midterm elections.

But just how bad is it for the blue team with a little less than four weeks left in the 2014 election? A new poll from Gallup has some pretty good clues.

The good news for Democrats: Americans in general aren't that enthusiastic about the 2014 election -- and that includes Republicans.

The bad news: Democrats are less enthusiastic at this point than they have been in at least the last four midterm elections. And that includes the big GOP wave year of 2010.

Here's a look at how the enthusiasm of Democrats and Democratic-leaning voters compares to the 1998, 2002, 2006 and 2010 midterms, according to three measures: whether people claim to be more enthusiastic than usual, whether they've given the election at least "some" thought, and whether they claim to be "extremely" motivated to vote:

You'll notice that, on all three measures, Democrats come in lower than any of the four previous midterms.

Here's the same chart for Republicans and GOP-leaning voters:

Again, they're not hugely motivated either. But they are at least more motivated than they were at this point in 2002 and pretty close to where they were in 1998 and 2006. In other words, as far as GOP enthusiasm goes, it's a pretty standard midterm.

Where you really start to see the difference, though, is when you compare the two parties:

Thanks to overall disinterest in the 2014 election, the enthusiasm gap between the GOP and Democrats at this point isn't as big as it was in 2010, but it's closer to that election than any other recent midterm.

These, of course, are national numbers, and the real 2014 campaign -- the battle for the Senate -- is taking place in a dozen or so key Senate races in which voters are being inundated with campaign ads and the two parties are out in full force. The picture in these states -- and the enthusiasm gap -- could conceivably be different, and Democrats have been pushing the so-called Bannock Street Project as their ticket to strong turnout in key states.

And enthusiasm, as even Republicans acknowledge, isn't a direct predictor of turnout. So the charts above don't mean 40 percent of Republicans and 30 percent of Democrats will vote come Nov. 4. It's not that simple.

But at the base level, it's clear Democrats have a much more difficult task in turning out their voters in the 2014 election than Republicans do. And according to this poll, it's the most difficult task they've faced in at least two decades.