Nancy Benac?and Julie Bykowicz

HOUSTON: Brawling from the get-go, Marco Rubio and Ted Cruz aggressively went after Donald Trump in Thursday night’s Republican debate over the front-runner’s positions on immigration, his privileged background and more.

The two men trailing Trump in the GOP campaign showed the increasing urgency of their effort to take him down before the billionaire businessman becomes unstoppable, criticizing him in an intensely personal manner.

The debate took place just days before the Super Tuesday round of mega-voting that could all but lock up the nomination.

When Trump faulted Rubio on a deal to buy a $179,000 house, the Florida senator shot back that if Trump “hadn’t inherited $200 million, you know where Donald Trump would be right now? Selling watches in Manhattan.”

In the night’s first rough exchange, Rubio accused Trump of shifting his position on deportation, hiring people from other countries to take jobs from Americans and being fined for worker violations. Joining in, Cruz criticized Trump for suggesting he alone had “discovered the issue of illegal immigration.”

Trump shot back at Rubio: “I hired tens of thousands of people. You’ve hired nobody.”

As for Cruz, Trump took a more personal tack, touting his own ability to get along with others and adding: “You get along with nobody. … You should be ashamed of yourself.”

Both Rubio and Cruz said Trump once had to pay a $1 million fine for illegal immigration hiring.

Rubio was the principal aggressor early on. Taking on Trump’s declaration that he’d build a wall on the Mexican border, Rubio declared: “If he builds a wall the way he built Trump Tower he’ll be using illegal immigration to do it.”

Trump insisted that even though officials in Mexico have said they won’t pay for the wall, “Mexico will pay for the wall.” And he said that because Mexico’s current and former presidents had criticized him on the issue, “the wall just got 10 feet taller.”

Trump, known for his frequent use of coarse and profane language on the campaign trail, scolded former Mexican President Vicente Fox for using a profanity in talking about Trump’s plan for the wall.

“He should be ashamed of himself and he should apologize,” declared Trump.

In the past, Rubio and Cruz had shown little willingness to take on the former reality television star when the national spotlight was the brightest. That changed in the ninth GOP debate of the presidential campaign as Trump appeared on track for the nomination.

The debate took place just a few days before 11 states hold GOP elections that could either cement Trump’s dominance or let his rivals slow his march to his party’s nomination. The debate’s location in Houston gave a nod to the primacy of Texas in that voting: There are 595 delegates at stake, 155 in Texas.

In opening statements, Ohio Gov. John Kasich addressed young people. He said, “You can do whatever you want to do in your life. America is an amazing country, where a kid like me can grow up to run for president.”

Retired neurosurgeon Ben Carson said in his opening remark that the United States is changing — and not for the better.