John Boehner could end this right now. He has the votes; he just doesn't have the guts to use them. If he put a "clean" bill before the House that funded the government at current levels, with no extraneous language about ObamaCare or other issues, it would pass with a bipartisan majority. The Senate would quickly pass it, the president would sign it and this particular little chapter would be over.

But Boehner won't do that, because conservatives in his caucus won't let him. They have hungered for this fight, they now have it, and they think they can win it. The question is why they think that way.

One way to answer that question is to look at the 80 conservative Republican congressmen who back in August sent a letter to Boehner, demanding that he refuse to pass a spending bill unless ObamaCare is defunded. By some accounts, that letter -- initiated by U.S. Rep. Mark Meadows of North Carolina, and backed by groups such as FreedomWorks and Heritage Action -- is the origin of this government shutdown.

So who are the members of this "suicide caucus," as it was dubbed by Charles Krauthammer?

Ryan Lizza, writing in The New Yorker, gives us a very useful breakdown:

"The members of the suicide caucus live in a different America from the one that most political commentators describe when talking about how the country is transforming. The average suicide-caucus district is 75 percent white, while the average House district is 63 percent white. Latinos make up an average of 9 percent of suicide-district residents, while the over-all average is 17 percent. The districts also have slightly lower levels of education (25 percent of the population in suicide districts have college degrees, while that number is 29 percent for the average district).

The members themselves represent this lack of diversity. Seventy-six of the members who signed the Meadows letter are male. Seventy-nine of them are white.

As with Meadows, the other suicide-caucus members live in places where the national election results seem like an anomaly. Obama defeated Romney by four points nationally. But in the 80 suicide-caucus districts, Obama lost to Romney by an average of 23 points. The Republican members themselves did even better. In these 80 districts, the average margin of victory for the Republican candidate was 34 points.

In short, these 80 members represent an America where the population is getting whiter, where there are few major cities, where Obama lost the last election in a landslide, and where the Republican Party is becoming more dominant and more popular. Meanwhile, in national politics, each of these trends is actually reversed."

For the record, five Georgia congressmen -- Jack Kingston, Paul Broun, Doug Collins, Tom Graves and Phil Gingrey -- were charter members of the "suicide caucus," which means their districts are included in the data above. The numbers were  compiled for Lizza by David Wasserman of the Cook Political Report.

In a series of tweets Monday, Wasserman expanded his numbers-based tutorial into why today's GOP caucus behaves as it does. Among his data points:

-- 48 percent of the House GOP caucus arrived in Washington after George W. Bush left, which is pretty astonishing. As Lizza points out, Meadows came to Washington just eight months ago. These are not your daddy's Republicans, and they have little loyalty to the party's current leaders.

-- In 1995, the last time we had a shutdown, the median Republican House district was R+6.8, meaning a Republican candidate had a natural advantage of 6.8 percentage points. That's a nice but not insurmountable advantage. Likewise, the median Democratic district seat was D+6.7.

That has changed dramatically. "In 2013, median Dem seat is D+11.8, median GOP seat R+10.2," Wasserman tweeted. In other words, these members are politically well-insulated from the heat generated by a shutdown, which means this could go on a while.

-- "In '95-'96, 79 of 236 House GOPers (33.5%) came from (congressional districts) Clinton won in '92. Today, just 17 of 232 (7.3%) come from CDs Obama won in '12."

-- "In '95, fewer than a third of House GOPers (73/236) came from CDs R+10 or more. Today, more than half (122/232) do."

These are the people, the districts and the "voters back home" who are dictating House Republican strategy. These congressmen have no incentive to moderate or compromise, and they almost literally live in a bubble where most people think exactly as they do. So as far as they're concerned, "everybody" does. And they act accordingly.