Julian Castro isn’t writing off some of the older potential Democratic presidential contenders, like former Vice President Joe Biden and Sens. Bernie Sanders and Elizabeth Warren.

But the 44-year old former San Antonio, Texas, mayor and Housing and Urban Development secretary under President Obama clearly likes to highlight that Americans are hungering for “a new generation of leadership.”

Castro on Wednesday took a major step toward running for the White House by announcing - through a video on his website - the launch of a presidential exploratory committee.

Julian Castro at the New Hampshire Institute of Politics last February. (Fox News)

Asked about potential candidates in their 70s or late 60s, such as Biden, Sanders and Warren, Castro said they “bring a lot to the table” and are “very talented, very accomplished, very important voices in the party. I hope they run.”

“I would never say somebody shouldn’t be in a position just because they’ve been around for 'x' number of years,” Castro explained in an interview with Fox News and a couple of local New Hampshire news outlets.

But, he emphasized: “I think you always need a mix of folks who have a lot of experience and then also folks who are bringing a fresh perspective. And I’m going to try and bring a fresh perspective.”

Castro grabbed headlines with his announcement – which he said would be followed by an official decision on Jan. 12.

Julian Castro during a visit to Nashua, N.H. (Fox News)

But the news came as fellow Texas Democrat Beto O’Rourke’s been enjoying plenty of buzz and lots of national media attention in recent weeks. The outgoing congressman who came close to defeating Republican Sen. Ted Cruz in last month’s midterm elections has excited activists and donors across the country as he mulls his own presidential bid.

“I’ve always assumed that this is going to be a crowded field,” Castro acknowledged.

“I think you have a lot of talented people who are thinking about it, including Beto,” he added diplomatically.

O’Rourke returned the compliment, telling Fox News: “Secretary Castro is an amazing person, did an amazing job as mayor of San Antonio as secretary of HUD in the Obama administration, I think he’s going to be a great candidate.”

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O’Rourke added that Castro’s move “doesn’t change anything that I’m doing because we just haven’t made a decision about anything.”

He explained he’s been focused on finishing his remaining weeks in Congress during the lame-duck session before spending “time with family and hopefully it becomes obvious to us what’s in the best interest of our family and country and pursue it.”

In his interview, Castro clearly took aim at President Donald Trump even without naming him, highlighting that Americans are “ready for leadership in Washington that is trying to unite us instead of divide us, that insists on opportunity for everybody instead of just opportunity for some people, that has integrity and character instead of what we’ve seen recently.”

Castro’s announcement – which allows him to raise money legally for a presidential bid - did not come as a surprise.

He’s been signaling that a White House run has been in the cards, telling reporters in recent weeks he was likely to launch a campaign. His trips this year to the early voting states in the presidential primary and caucus calendar – including three stops in New Hampshire – also were a calling card regarding his 2020 intentions.

Castro’s move puts him ahead of most potential rivals for the nomination. Only outgoing three-term Rep. John Delaney of Maryland – who announced his run for president in July of last year – has tossed his hat officially into the ring.

Many others are expected to follow soon.

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Looking ahead to the possibility of a field of up to 20 candidates or more, Castro said: “That’s going to be fantastic for Democrats because you’re going to get to hear from any number of people with different perspectives and everybody’s going to have their voice heard and I think that’s going to be cathartic in fact for the party, after some of the bitterness of 2016.”

But, he said his move wasn’t an attempt to beat other White House hopefuls to the punch.

“For me, I’m going on my own timeline,” he explained. “I’m going to get out there and talk to folks in New Hampshire and across the country regardless of what other people are doing.”

Before heading out on the campaign trail, Castro and his twin brother, Rep. Joaquín Castro of Texas, will be in New York on Thursday evening, for some national exposure. Both Castors are scheduled to sit down with Stephen Colbert on "The Late Show" on CBS.

Fox News’ Peter Doocy contributed to this report.