HOUSTON (CN) - Marco Rubio flustered frontrunner Donald Trump by calling him out on his history of hiring undocumented immigrants, while Ted Cruz disappointed his hometown with a lackluster performance in Houston Thursday night as a crowd demonstrated across the street.
Nearly half of the 1,237 delegates needed to win the Republican nomination will be up for grabs on Super Tuesday next week, with Republican voters going to the polls in 12 states.
Texas' 155 delegates are the biggest prize, and before the Thursday debate at the University of Houston, pundits said Cruz had to turn in a high-quality performance to regain the momentum he's lost since winning the Iowa caucuses.
Cruz and Rubio are essentially tied for second place in the delegate count behind Trump, who holds a commanding lead after three straight victories, in New Hampshire, South Carolina and Nevada.
Dozens of Houston police and Harris County sheriff's officers set up a perimeter around the campus as a rally broke out an hour before the debate.
With a bullhorn slung over her shoulder, Alma Cooper, 60, a longtime Houstonian and native Mexican said, "We're trying to bring awareness to the people about what the Republicans are. And at this time the Republicans' campaigns are just to see who hates immigrants more and who wants to make them suffer more."
The large crowd chanted: "Stop the hate. Stop the fear. Immigrants are welcome here."
Asked what she thought about Trump and his idea to deport all of the estimated 11 million paperless immigrants in the United States, then let the good ones back in, Cooper said, "He's just a business showman. He knows how to get the people's attention. I don't think he has the knowledge and experience to lead the country."
Trump stood by his statements on immigration during the debate and his insistence that he could make Mexico pay for a wall along the 1,989-mile U.S. border.
Telemundo moderator Maria Celeste Arrás told Trump that Mexico's former president Vicente Fox recently said, "I'm not going to pay for that fucking wall."
But Trump remained defiant. "The wall just got 10 feet taller," Trump said.
"We're going to make them pay for that wall," Trump said. "It's $10 billion to $12 billion if I do it. If these guys do it, will cost $200 billion," he said, pointing at Cruz and Rubio.
Rubio came right back at the real-estate developer. "You're the only person on this stage who has been fined for hiring illegal people to work on your jobs."
Cruz backed Rubio up. "Marco is right. A federal court found Donald guilty of conspiring to hire people illegally and entered a $1 million judgment," the Texas senator said.
Rubio on Thursday showed a knack for punchy on- liners that jarred Trump.
"If he builds the wall the way he built Trump Tower he'll be using illegal immigrants to do it," Rubio said. "Here's a guy who inherited $200 million. If he hadn't inherited $200 million you know where he'd be? Selling watches in Manhattan right now."