If anyone still needs proof that presidential campaigns have become more about media moments than actual policy positions and leadership qualities, Beto O'Rourke and Julián Castro offered a case study this past week in how things really work.

Most Americans are paying scant attention with the first caucuses and primaries more than seven months away. For those of us watching every move and reporting every gleaning, national-media coverage of what the two Texas candidates had to say Thursday was quite telling.

Castro, the onetime Housing and Urban Development secretary in the Obama administration and former mayor of San Antonio, became the fifth Democratic candidate Thursday to appear on a Fox News town hall. The one-hour program was interesting, yet produced nothing to provoke President Donald Trump on Twitter, even when Castro stated pointedly, "A few years from now — whether it's 10 years from now, 20 years from now — we're going to look back on this as Americans … and say 'What in the hell was wrong with that president?' "

A close runner-up line was Castro's comment on Trump ruining long friendships with close allies: "I mean, who gets into a fight with Canada?" Castro asked, provoking audience laughter and applause. "But somehow this president did."

To his credit, Castro, the grandson of a Mexican immigrant, effectively won over the Maricopa County studio audience in Arizona and acquitted himself with confidence on the Republican red-meat issues of immigration, abortion and, of course, Hillary Clinton.

It was unlikely, however, to lift him from his position at or near the bottom of the national polls.

O'Rourke, the former El Paso congressman who lit up Texas and the country with his near-miss run for the U.S. Senate against Ted Cruz last year, appeared the same day on MSNBC's "Morning Joe." He wasted no time in attacking front-runner Joe Biden.

"I'm not exactly sure what he believes or what he should apologize for," O'Rourke said. "I only know that this country should be able to do far better."

It remains to be seen whether O'Rourke's anti-Biden call-out elevates him in the polls; he has more support than Castro but lags well behind Biden and Sens. Bernie Sanders, I-Vt., and Elizabeth Warren, D-Mass., at the front of the pack. But he drew far more coverage for his interview than Castro did for his solo hour on Fox News.

And there lies the problem for Castro. His comprehensive immigration reform plan could have been constructed only by someone with a nuanced understanding of the border, U.S.-Mexico history, the role of undocumented workers in the U.S. economy and the importance of immigration historically to this country.

Yet complex public-policy issues can't be reduced to the same catchy sound bites as an attack on another candidate's vulnerabilities. Fox town hall moderators Bret Baier and Martha MacCallum invited Castro more than once to take some time to attack other Democrats. He demurred.

"I need to introduce myself," an exasperated Castro said at one point.

O'Rourke had no such qualms on "Morning Joe."

"You've got to ask yourself where Joe Biden is on the issues that are most important to you: Did he support the war in Iraq that forever destabilized the Middle East?" O'Rourke asked. "Does he really believe that women of lower incomes should be able to make their own decisions about their own body, be able to afford health care in order to do that? He supported the Hyde Amendment; he now opposes the Hyde Amendment."

Castro showed very well on Fox on Thursday, but Beto won the day. For me, it is more evidence that the cerebral, policy-driven Castro is not going to catch fire. Barring a miracle, he — like most of the candidates — will need to give way to front-runners by the end of February if the focus is to become stopping Trump from winning a second term.

O'Rourke's chances are better, but let's set him aside. As I watched and listened Thursday, I found myself thinking more about Castro. A lawyer, he was making a strong case to become the next attorney general should voters elect a Democrat. His proposal to decriminalize border crossings by undocumented workers, a return of sorts to status quo before 9/11, and his call for a Marshall Plan for Central America to reverse the outward flow of migrants north make good sense.

His call for a rapid expansion of asylum courts and more humane treatment of detained migrants also sounded a common-sense note after two years of expensive militarization, heartbreaking family separations, bickering about a multibillion-dollar border wall and threats to our Mexican neighbors.

Who better to forge new border policies than a product of the American dream? It's not all about the presidency. Castro seems like a real national asset but not a real contender for the Democratic ticket.

Robert Rivard is the editor and publisher of the nonprofit Rivard Report in San Antonio. He wrote this article for the Washington Post.