Updated at 12:11 p.m. Tuesday with the results of a poll of Texas voters.

Julián Castro and Beto O'Rourke will attempt to reverse the trajectory of their fledgling presidential campaigns as Democrats stage their second presidential primary debates this week.

The showdowns, on two separate nights, could boost or break either candidate.

O'Rourke, the former El Paso congressman, is hoping to rebound Tuesday night from a bad performance in the first round of forums in Miami. Castro, the former San Antonio mayor who will debate Wednesday, mauled him during an exchange over whether to make illegal entry into the country a criminal or civil violation.

O'Rourke got some good news ahead of Tuesday night's debate.

A poll conducted by the Center for Opinion Research at the University of Texas at Tyler showed the former congressman leading among Texas voters in the Democratic presidential primary. The survey showed O'Rourke with a 27% to 24% lead over former Vice President Joe Biden. Vermont Sen. Bernie Sanders was third at 15%, followed by Massachusetts Sen. Elizabeth Warren at 11% and California Sen. Kamala Harris at 9%.

The poll of 465 registered Texas voters found that O'Rourke led President Donald Trump in a head-to-head matchup by a 49% to 37% margin.

Castro struggled in his home state poll. He was the first choice of only 2.4% of Texans surveyed.

Though Castro enjoyed an initial surge in fundraising after the first debate, he remains buried in most polls at around 1%. That's off the pace needed to get a critical invite to the next round of debates in September at Texas Southern University in Houston.

Analysts say Castro and O'Rourke, particularly the latter, must command the debate stage this week and somehow connect with Democrats watching on television or catching up through the later news coverage.

Texas is the home of Democratic political legends like Lyndon B. Johnson, Ann Richards, Lloyd Bentsen and Barbara Jordan. Slogans indicative of the state's bravado include, "Don't Mess with Texas"; "Texans don't run from a fight, they run to the fight"; and "Texas is a blend of valor and swagger."

O'Rourke and Castro haven't shown that kind of gravitas.

"When you think of Texas, you think of words like outsized and dominant," said Aaron Kall, director of debate at the University of Michigan. "Maybe their personalities don't fit that mode. A little more swagger, personality and confidence could help."

Jane Hamilton, a former chief of staff for Rep. Marc Veasey, D-Fort Worth, and a board member of the progressive group Annie's List, said the Texans have to show they can slug it out with Trump.

"Beto and Julián don't have to prove that they are smart enough, but they need to demonstrate that they are tough enough to take a roundhouse from Donald Trump and deliver back an even harder blow," she said.

Eric Cedillo, a Dallas lawyer who has worked with both Texans, says he expects O'Rourke to rebound and Castro to have another good performance.

"Both of them have a tough row to hoe," Cedillo said. "O'Rourke will be able to show a moderate appeal. He won't get attacked by Castro this time."

The stakes for Castro are even more critical.

"Castro has to get his poll numbers up or he's not in the third debate," Cedillo said.

Looking for a comeback

O'Rourke rode into the presidential contest after losing to incumbent Republican Sen. Ted Cruz by a 2.6% margin, a race that made him a national sensation.

But after he launched his presidential bid, his campaign lost momentum, including a disastrous debate performance in which he struggled to crisply answer questions and appeared stunned when Castro said he needed to do his homework.

O'Rourke has a history of lackluster debate performances. He struggled during his first debate against Cruz but rebounded when the two faced off several weeks later.

Now O'Rourke needs another comeback, but this time just to stay relevant.

"Beto needs to define himself more to the world of Democratic voters," said Kelly Dietrich, founder of a candidate training group called the National Democratic Training Committee. "Who is Beto? Why is he running?"

Democratic presidential candidate, former U.S. Rep. Beto O'Rourke, attended the Manchester Democrats' annual Potluck Picnic at Oak Park in Manchester, N.H., on July 13, 2019. (Cheryl Senter / The Associated Press)

Dietrich said O'Rourke could answer those questions, though rebounding will be tough.

"Trying to convince voters to give you a second glance and change their minds is more difficult," he said.

But Dietrich and others say O'Rourke has the talent to turn it around.

Simple changes, like the way he answers questions, will help.

"He showed in his second debate against Cruz that he can rebound," said Dallas County Judge Clay Jenkins, who worked on Barack Obama's presidential campaign. "He's got to get the attention on him. ... He needs to give direct answers to questions before pivoting to a broader message."

Jenkins said it's important for O'Rourke and Castro to show toughness.

"Democrats want someone who is in command and control and capable of beating Donald Trump," Jenkins said.

Target Joe Biden?

Castro needs another strong debate performance to raise his profile and be relevant when the field of candidates winnows.

The former U.S. housing secretary has command of the issues, analyst say. But voters still don't know him.

Kall said Castro was lucky to be staged with Biden, the front-runner who stumbled during the first debate. That's when Harris challenged his 1970s-era stand on school busing. Harris is also featured on the final night, and many of Biden's rivals will take aim at him, hoping for an attention-grabbing moment.

"Being on the second night is essential because that debate gets more attention," Kall said. "Castro has as good of a chance as Kamala Harris to have that kind of moment."

Julian Castro, Democratic presidential candidate and former secretary of Housing and Urban Development, speaks during a candidates forum at the 110th NAACP national convention on July 24, 2019, in Detroit. (Carlos Osorio / The Associated Press)

Whether or not Castro will go after Biden is unclear.

"He'll have a plan," Cedillo said. "He'll be ready."

But he'll need an uptick in the national standings to appear onstage with other qualifying candidates for the debate in Houston.

"If you're not in that third debate, it's probably over," Kall said.

Still a large field

Analysts will be watching the debate to see how well Biden performs, particularly if there's another showdown with Harris.

On the first debate night, the leading candidates in the polls are Sanders Warren. It's hard to predict their strategies.

Kall said all of the candidates will feel pressure to meet expectations.

"A poor performance here and you have to wait two months to redeem yourself," Kall said.

Dietrich, a veteran Democratic Party consultant, said it will be interesting to see which of the lower-tier candidates, if any, gain traction.

To illustrate how big the Democratic field is, long-shot candidates Andrew Yang, a businessman, and Sen. Michael Bennet of Colorado are having a pre-fight beef.

In what's being described a mock Twitter fight, Yang announced that he would be attacking Bennet at the debate, which is more notice than Castro gave O'Rourke.

I would like to signal to the press that I will be attacking Michael Bennet at next week’s debate. Sorry @MichaelBennet but you know what you did. — Andrew Yang (@AndrewYang) July 26, 2019

Just confirmed with debate officials that @AndrewYang’s microphone will be muted during my rebuttal. https://t.co/YmR7HvkfRF pic.twitter.com/oT3Pe9shai — Michael Bennet (@MichaelBennet) July 26, 2019

"What did Bennet do to Yang?" Dietrich joked. "I want to know."

Attack lines aside, analysts say O'Rourke and Castro should be wary of joining the large parade of candidates moving to the left.

"They need to avoid talking about any issue in broad ideological terms that leaves them just another in a group of second-tier Democrats fighting for liberal votes," Hamilton said. "They need to break down positions on issues like health care and immigration and justice reform into the specific ways that affect individual lives."

Tuesday

From the top tier: Elizabeth Warren and Bernie Sanders

From the middle tier: Beto O'Rourke, Pete Buttigieg and Amy Klobuchar

From the lowest tier: Marianne Williamson, John Delaney, John Hickenlooper, Tim Ryan and Steve Bullock

Wednesday

From the top tier: Kamala Harris and Joe Biden

From the middle tier: Julian Castro, Andrew Yang and Cory Booker

From the lowest tier: Jay Inslee, Kirsten Gillibrand, Tulsi Gabbard, Michael Bennet and Bill de Blasio