(CNN) There's zero question as to who the buzziest candidate -- or potential candidate -- in the 2020 Democratic presidential race is. It's Beto O'Rourke. And it's not close.

But for all the excitement that the former House member from Texas has built after his near-miss challenge to Sen. Ted Cruz (R) in 2018, there's still a whole lot that people don't know about him. And more importantly, a lot that O'Rourke doesn't know.

Here's a quick rundown of the lowlights:

So...

The reality of O'Rourke -- at least at the moment -- is people are in love with the idea of him. A young, good-looking, authentic politician. Someone who isn't focused on telling people what to think but instead wants to hear what they think. Explaining his unorthodox approach, O'Rourke told Johnson:

"That's a problem when you're like, 'It will be a wall,' or 'It will be this,' or 'We can only do it with this,'" O'Rourke said when asked why he doesn't have firm stances. "The genius is we can nonviolently resolve our differences, though I won't get to my version of perfect or I, working with you, will get to something better than what we have today..."

Which sounds good! In theory!

The problem that emerges in the story for O'Rourke is that he comes across as something of a lightweight -- all style and no substance. The answer to every policy question can't simply be, "Man, I don't know. We are going to have to talk to everyday Americans and then roll our sleeves up and get something done for the country." That's not how politics works -- not now and not ever.

To be clear: Presidential campaigns are not, typically, filled with meaty policy debates. Much of how people make up their minds about who to support comes from a feel for the candidates that tends to be based on an instinct or observed perception as opposed to a detailed study of their policy positions. (Some people, of course, do make their choice based on either a single policy or a set of policies; it's just not the majority of people.)

Think back to the two most recent successful campaigns for president. Neither "hope" and "change" nor "Make America Great Again" elucidated a policy position. Both slogans were designed to evoke a feeling within people -- and they worked.

All of which means that O'Rourke doesn't have to have a position on every single issue facing the country in order to win. After all, outside of trade and immigration, Donald Trump didn't have a working knowledge of lots and lots of issues. Remember when he as a candidate had NO idea what the phrase "nuclear triad" referred to?

But he does need to understand that the attack from his Democratic opponents -- and maybe from Trump too -- will take this form: This guy seems good and talks a good game. But he doesn't actually know much of anything. And do we really want to nominate someone like that to run against President Trump?

Now, O'Rourke isn't a candidate for president yet. Which means he still has some time to bone up on issues to the point where he is more conversant than he demonstrated in the WaPo interview. He is currently spending his time driving around the country, a trip he detailed in a Medium post on Wednesday afternoon

"Have been stuck lately. In and out of a funk," he wrote. "It's been more than twenty years since I was last not working. Maybe if I get moving, on the road, meet people, learn about what's going on where they live, have some adventure, go where I don't know and I'm not known, it'll clear my head, reset, I'll think new thoughts, break out of the loops I've been stuck in."

Make no mistake: O'Rourke can't keep giving interviews like the one in the Post if he wants to fulfill predictions that he will be a top-tier candidate for Democrats in 2020. Appearing the part will only get him so far -- especially in a field with the likes of Joe Biden, Elizabeth Warren and others who have spent years thinking through their policy positions and can explain it to voters in a concise and effective way.