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 that Trump had 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, clearly reflecting the growing sense that Trump is 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.
To date, Trump has proved largely immune to traditional political attacks, something he revels in.
"I seem to have a very good track record when they do go after me," he said in advance of the debate.
One of the early casualties of the GOP presidential race, Sen. Lindsey Graham of South Carolina, showed no reluctance Thursday to assail Trump head-on, calling him "a nut job" who's likely to win the GOP nomination but lose the general election.
Graham singled out Trump's assertion that illegal immigration from Mexico brings rapists and drug dealers into the U.S.
The debate audience included former President George H.W. Bush, 91, and his wife, Barbara — who missed out on the chance to see their son Jeb take part. He dropped out of the race after a poor showing in the first states to vote.
Thursday's debate, with CNN and Telemundo as partners, is the only one of the season steered to a Spanish-speaking as well as English-speaking audience, so immigration could be a closely watched issue.
Vice President Joe Biden said during a visit in Mexico on Thursday that some of the campaign rhetoric about Mexico has been "dangerous, damaging and incredibly ill-advised." Biden said the GOP candidates "do not represent the view of the vast majority of the American people."
Trump won Nevada's presidential caucuses on Tuesday with more than 45 percent of the vote, scoring his third consecutive primary victory in dominant fashion. Rubio edged Cruz for runner-up for the second straight time, with former Florida Gov. Jeb Bush — now out of the race — Ohio Gov. John Kasich and retired neurosurgeon Ben Carson far off the pace.
Seeking to become the Trump alternative, Cruz and Rubio have significant liabilities of their own.
Cruz came into the debate at the weakest point of his campaign after a staff shake-up and three consecutive third-place finishes.
Rubio, meanwhile, is barely past a prime-time flop. The Florida senator repeated himself several times in a New Hampshire debate less than three weeks ago, triggering what he now calls "the New Hampshire disappointment."
He avoided a similar mistake in the subsequent debate, but he's under the microscope for anything that suggests the 44-year-old legislator isn't sufficiently prepared to move into the White House.
Associated Press writers Laurie Kellman in Washington, Will Weissert in Houston and Steve Peoples in Las Vegas contributed to this report.