Former secretary of housing and urban development Julián Castro plays on his charisma and youth.

But as he looks towards running for president in 2020 (earlier this week, Castro told NBC "I have every interest in running"), the Texan Democrat is showing a harder edge.

Consider what happened on Thursday, when NBC News asked Castro whether he thought the presumptive Democratic field for 2020 looks too old.

The 43 year-old's response was hardly docile.

"You need youthful voices, energetic voices. And so if Vice President Biden or Senator Sanders or others decide to run, I think that they're going to be well received. Obviously, they have folks who believe in them. I'll tell you that I believe that in 2020, the American people are going to be looking for a new generation of leadership... I believe that in 2020 that that's going to be a year in which the American people look for new leaders."

Notice the language he's using.

Because in his double reference to "new," and in his "look"/"looking", "leader"/"leadership" pledges, it's clear that Castro is already sculpting his media messaging for the next election. It's equally clear what his message is going to be: "I'm the fresh face you need to take on Trump and win, I'm not the has-been-Biden or the geriatric Bernie."

It might work, but it's also a very bold approach to take while we're still so far away from the election. After all, even if he couches his rhetoric with qualifications, these aggressive jabs risk alienating Bernie Sanders and his legions of door knocking activists. Similarly, by attacking Biden, Castro also risks getting on the wrong side of the Obama fundraising dynasty.

And if you don't have activists and donors, you ain't winning a U.S. presidential election.

On the flip side, Castro is showing energy and courage in getting in front of the pack. Considering his limited name recognition compared to the other two men, Castro probably feels he has no choice. In the coming months, expect him to double down on the talk show circuit.

Oh, and expect President Trump to take notice and start firing off some tweets. (What do you suppose Castro's nickname will be?)