HOUSTON – The eyes of the political world were on Texas Thursday night as 10 Democrats took to the stage in Houston to talk about everything from President Donald Trump to trade.

San Antonio's former mayor, Julian Castro, was in the middle of some spirited exchanges. Whether planned or not, he found himself on the opposite side of former Vice President Joe Biden.

"Every time something good about (former President Barack) Obama comes up, (Biden) says, ‘Oh, I was there. That's me too.' And then every time someone questions the administration, we were both a part of he says, ‘Well, that was the president.' He wants to take credit for Obama's work but doesn't want to answer to any questions," Castro said during the exchange with Biden.

"I stand with Obama all eight years — the good the bad and the indifferent. I did not say I did not stand with him," Biden said.

Video: Debrief: Steve Spriester's debate takeaways 

Immigration and health care were the two big topics Castro and Biden debated on. The economy and gun control were also up for debate.

The two recent mass shootings in Texas became a part of a heated discussion on stage.

El Paso native former Rep. Beto O'Rourke reacted after shoppers were gunned down in a Walmart in the border town last month and another shooting in the Midland-Odessa area. He said he would implement a mandatory buyback program for AR-15s and AK-47s if elected.

"In Odessa, I met the mother of a 15-year-old girl who was shot by an AR-15, and that mother watched her (daughter) bleed to death because so many people were shot by that AR-15. There weren't enough ambulances to get to them. Hell, yes, we're going to take your AR-15, your AK-47. We're not going to allow for it to be used against fellow Americans anymore," O'Rourke said during the debate.

Regarding immigration, several of the candidates said they would loosen restrictions on immigration put into place under the Trump administration.

Massachusetts Sen. Elizabeth Warren said she would expand pathways to citizenship but noted a broken system.

"Down at the border, we have to rework this entirely. A system right now that cannot tell the difference between a terrorist, a criminal, and a 12-year-old girl is not a system that is keeping us safer, and it is not in our values," Warren said.

O'Rourke said he will lead an effort to make sure immigration laws are rewritten.

Castro said the Deferred Action for Childhood Arrivals program would remain in place, saying "We're not going to give up protections for anybody."

Pride and excitement beamed from students and staff members on the Texas Southern University campus where the debate was held.

Among the thousands of people at TSU for the debate, at least a few of them had San Antonio connections.

"We just need to vote and get Trump out of office, because he really is destroying our moral fabric and what we stand for as a nation," said Phillip Grant, a San Antonio area native.

"It's a big, big deal for my university, my alma mater — this feeling that hopefully our next president was on that stage tonight," said Jacoby McPherson, a San Antonio resident and TSU alumnus.

No matter where the attendees were from, they all seemed be interested in hearing the candidates talk about issues they say are plaguing the country, such as gun control, immigration and race relations, and they all had varying opinions about who came out on top.

"Everything that Bernie said, he was saying in 2016 and he still has that same conviction for it. The thing that stood out in this presidential race was getting a thousand bucks from Andrew Yang. I mean, everyone could use that," said Alan Ambrister, a Houston resident.

"What did pop in my mind was at least every candidate is working toward a common goal. Now how they come upon that common goal, it can go either way," said Jeremiah Cooper, a San Antonio native, referring to gun control.

Since the debate was held on a college campus, there is an assignment associated with it. A political science teacher handed out QR codes to her class for them to create a poll to see who came out on top. For the results, however, they'll have to wait until the election in 2020.