AUSTIN, Texas -- Democratic presidential candidate Julian Castro knows he’s not the frontrunner right now.

But the former HUD Secretary and San Antonio mayor continues to emphasize, it’s early.

“I have no doubt that as I get in front of voters in any state in our country, that I'm going to gain traction,” he said.

Castro has vowed to campaign in all 50 states. But he’s been focused on building support among Latinos and has called himself the antithesis to Donald Trump.

“He has basically put a target on the back of a lot of Latinos,” Castro said. “And so I believe that my candidacy is going to have special meaning, is going to resonate with the Latino community.”

Castro ruled out any notion that he’ll challenge Sen. John Cornyn, R-Texas, if his presidential campaign fizzles out early. But he said his twin brother, Congressman Joaquin Castro, is still deciding.

“I’m not going to run for Senate. I’m running for President. My brother is thinking about running for Senate. He’s going to make a decision in the next few weeks,” Castro said.

Click the video link above to watch our full interview with Julian Castro, including his take on Trump’s border wall, the sentencing of the president’s former campaign chairman and whether Beto O’Rourke jumps into the race.