Stockman was first elected to the House of Representatives when he defeated 42-year incumbent Democrat Jack Brooks in the GOP's 1994 wave. He only served two years (he was defeated by Democrat Nick Lampson in 1996), but that was enough time to make a name for himself.

In the spring of 1995, Stockman published an article accusing the Clinton Administration of having staged the raid on Waco as a way to justify an assault weapons ban. "Waco was supposed to be a way for the Bureau of Alcohol, Tobacco and Firearms and the Clinton administration to prove the need for a ban on so-called assault weapons," he wrote, adding that for Congress to agree to pass a ban, "an incident had to be encouraged to happen."

Fast-forward to 2013: Within a few weeks of making it back to Congress after a 16-year hiatus, Stockman was once again blowing up over gun control. And while he didn't accuse President Obama of "premeditated murder" (as he had Janet Reno), he deemed Obama's proposals "unconstitutional and unconscionable," threatened to file articles of impeachment over them, and compared the President to Saddam Hussein.

Opposition to any form of gun control is central to Stockman's politics. Also within days of returning to Congress, he introduced the "Safe Schools Act," which would repeal federally-mandated "gun free zones" around schools.

And why stop at arming school officials? Stockman's 2014 re-election campaign is selling bumper stickers that read: "If babies had guns they wouldn't be aborted."

As you'd expect from all this, Stockman is a firm member of the House Republicans' "ultra" caucus—those members who have been making life difficult for their chamber's leadership. He was one of 10 Republicans to not vote for John Boehner as Speaker (he voted "present") in January, and he was among those who had no qualms about Cruz's efforts to shut down the federal government in order to repeal Obamacare this fall. He even claimed that the 1995 shutdown had boosted (yes, boosted) the GOP—never mind that they lost seats (and the White House) the following year.

By contrast, Cornyn is the Senate minority whip—an obvious target for groups targeting the current GOP leadership—and his September vote against an early Cruz attempt to defund Obamacare bill led the Senate Conservatives Fund to label him a "turncoat." (Oh, and Cruz had rather pointedly declined to endorse Cornyn.)

Cornyn did end up voting against the final shutdown-ending deal in October, however. He has been watching his right flank in recent years, eager to not leave obvious openings. So it's fitting that his vote against Cruz's pre-shutdown procedural maneuver is arguably his highest-profile split with Stockman this year: From the perspective of Cruz's allies, that vote was less about where Cornyn stands on any particular issue than about which side he's on—and how far he's willing to go to manifest it.

And there's no doubt that Stockman is happy to go very far.

In a letter he sent to his colleagues during his first term, Stockman didn't just compare homosexuality to bestiality—he lumped in premarital sex as well. He wrote: "[Our children] are taught that the problem with sex is not that it is wrong to engage in homosexual, bestial, underage, or premarital sex, but that it is wrong to do so without protection." The context of that letter was a bill he had introduced: the Child Protection and Ethics in Education Act. It called for an investigation into the studies Alfred Kinsey had conducted about human sexuality in the 1940s.

The Violence Against Women Act? "It’s called a women's act, but then they have men dressed up as women, they count that. Change-gender, or whatever. How is that—how is that a woman?" (Cornyn voted against the bill as well.)

Global warming? Stockman dismissed it as "the new fad."

Then again, it's not like Cornyn is worried about climate change. But can Cornyn claim to have gone all the way to Copenhagen during the 2009 global conference on global warming to take part in a counter-conference denouncing the scientific consensus on the issue? Nope, though Steve Stockman sure can. If you click on nothing else in this piece, click on this link to the New York Times article on that counter-conference. It features a picture of Stockman wearing a dramatic red mask over his eyes because "believing in global warming was like wearing a blindfold."

And he isn't content to support drilling for oil off the coast of California (which "liberal hatred of science and human progress" is preventing). He justified it by tweeting that: "The best thing about the Earth is if you poke holes in it oil and gas come out."

If you are waiting for an appointment in his office, the National Review reports that you can flip through a book called "Mixing Church and State God's Way." (Amazon's description: "A pastor... tells how we will lose everything if we do not stand up to the liberals and Muslims.")

Then, there's immigration. While Cornyn voted against the immigration reform bill that passed the Senate this summer, you may remember that one of the debate's flashpoint was his proposed amendment to significantly toughen border security as a condition for undocumented immigrants to apply for green cards. While Cornyn's amendment was labeled a "poison pill" because it would have led to an unraveling of the coalition that had put together the bill at hand, conservatives like Red State's Erick Erickson saw it very differently. That could hurt Cornyn in a Republican primary against an opponent who describes the Senate legislation as the "unconstitutional" "amnesty bill."

Stockman even warned that: “We’re going to have a Gang of Millions, because you can watch this bill as it progresses through the House committees that they will rise up against it and it will fail."

Recently, Stockman rushed to the defense of a University of Texas college group that had organized a campus-wide "game" it had called "Catch an Illegal Immigrant."

And then there are ethical questions surrounding Stockman: In late November, the Houston Chronicle published an expose into the 17 corporate identities Stockman has set up in four states and the British Virgin Islands—about which he has not filed federally required disclosures.

And just one week earlier, the Chronicle had reported that Stockman's campaign offices had to be shut down because "campaign staffers and volunteers had been both working and sleeping there, even though the commercial building was considered unsafe for human habitation" and was found to have 14 fire code violations!

That's not the kind of coverage you hope for in the weeks before you launch a statewide run. But it hasn't stopped Stockman. He waited 16 years to get back to the House—and he is gambling it all in his first term back to go after a powerful, well-financed senator from a mega-state in which campaigns are extremely expensive. It's hard to make sense of, really, but just like that Stockman did secure himself a very very big platform. Based on all the attention he's managed to get as a House back-bencher this year alone, imagine what he'll do and say, unleashed in a Senate campaign in which his whole goal will be to run to Cornyn's (far) right. Not that he'll have any difficulty doing that.