SIMI VALLEY, Calif. (CBSNewYork/AP) — Donald Trump was again center stage when 11 Republican presidential candidates square off in their second debate on Wednesday.

The candidates faced off at the CNN-sponsored debate at the Reagan Presidential Library in Simi Valley, California — with Ronald Reagan’s presidential plane as their backdrop. The lineup was the same as last month’s opening debate, with one notable addition: former Hewlett-Packard chief executive Carly Fiorina, the only woman in the GOP field.

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In his own introductory speech, while many other candidates first spoke about their professions and family lives, Trump focused on his business experience.

“I’m Donald Trump. I wrote the art of the deal – not in a braggadocious way, I’ve made millions and millions of dollars dealing with people from all over the world,” Trump said. “And I want to put that talent to work for this country.”

Even before Trump spoke, he was the subject of flattering comments. Former Arkansas Gov. Mike Huckabee – after disparaging on the policies of liberals and the left, said, “I think we are in fact the A Team. We have some remarkable people, and in fact, not only are we the A Team, we even have our own Mr. T” – referring to Trump.

But the debate was far from a love-fest. As CBS2 Political Reporter Marcia Kramer reported, the top-tier candidates sunk into name calling and mudslinging after the very first question.

As the debate began, moderators then brought up a remark by Louisiana Gov. Bobby Jindal, who said he thought Trump was “dangerous” and would amount to “a hothead with his finger on the nuclear codes.”

Fiorina, who has criticized Trump sharply in recent weeks, said it was up to voters to decide whether Trump was “dangerous,” but called him an “entertainer.”

Trump responded, “I may be an entertainer because I’ve had tremendous success – with number one bestsellers all over the place, with ‘The Apprentice,’ and everything I’ve done. But I will tell you this – what I am far and away greater than an entertainer is a businessman – and that’s far and away the kind of thinking this country needs.”

But some of the other candidates did not hesitate to pile on against Trump – particularly when Trump said Sen. Rand Paul (R-Kentucky) should not even be on the stage since he is polling at No. 11.

Paul fired back, criticizing Trump’s “language” and “character,” and his calling opponents “short, tall, fat, ugly – my goodness that happened in junior high. Are we not all above that?”

Trump in turn remarked, “I never attacked (Paul) on his looks, and there’s plenty of subject matter there.”

Trump also squared off against Republican Gov. Scott Walker, who accused Trump of lacking experience and being heavy on rhetoric.

“We don’t need an apprentice in the White House,” Walker said. “We have one right now.”

Trump responded, “In Wisconsin, you’re losing $2.2 million right now. I would do so much better than that.”

Friction also erupted between Trump and former Florida Gov. Jeb Bush, who has become the real estate mogul’s top target.

Bush tried to take on Trump directly in the debate’s early moments but was repeatedly interrupted by the GOP front-runner. As Bush tried to finish an answer, Trump chimed in: “More energy tonight, I like that.”

Trump’s jab was a reference to his frequent critique that Bush is “low energy.”

Trump also called former New York state Gov. George Pataki, who was not on the stage, “a failed governor in New York – he wouldn’t be elected dogcatcher right now.”

For his part, New Jersey Gov. Chris Christie began the debate by saying President Barack Obama had drained America of hope.

Christie used his introduction to ask CNN to turn the camera from him to the audience. He asked the crowd in the Ronald Reagan Presidential Library to raise their hands if they believed their children had a better future due to Barack Obama. No hands went up.

Christie promised to reverse that.

It was believed to be the largest debate field in modern political history, underscoring just how jumbled the fight for the Republican nomination remains with five months to go before the Iowa caucuses.

The candidates went on to discuss foreign policy – in particular, President Obama’s Iran deal, the global positions of Russia and China, and the Syrian refugee crisis.

U.S. Sen. Ted Cruz (R-Texas) received applause as he made a list of what he believed were the flaws of the Iran deal.

Trump said the Iran deal was “terrible,” but added that there needs to be more focus on North Korea.

“You have this maniac sitting there, and he actually has nuclear weapons,” Trump said.

The issue of same-sex marriage was also raised. Moderators directed a question at Huckabee about his support for Rowan County, Kentucky Clerk Kim Davis, who was placed in jail after refusing to issue licenses for same-sex marriages.

Huckabee accused the U.S. Supreme Court of “judicial tyranny,” saying “ninth-grade civics” was enough to prove that “the courts cannot legislate.”

Bush agreed that Davis should not be forced to issued marriage licenses to same-sex couples if she believed it was against her faith, but argued that someone else in her office should be allowed to do it.

Moderators then pitted Trump against Christie on the issue of immigration. Trump has said he wants all undocumented immigrants to be deported, while Christie has said mass-deportation is not realistic.

Trump emphasized that he wanted to build a “wall that works” along the U.S. border with Mexico, and also wants to be sure that all those with criminal records are removed at once.

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“We have a lot of really bad dudes in this country from outside, and I think Chris knows that already – they’re gone,” Trump said. He characterized the illegal immigrants involved in crime as “gangs all over the place – Chicago, Baltimore, no matter where you look.”

“We’re going to have a country again,” Trump said. “Right now, we don’t have a country. We don’t have a border, and we’re going to do something about it.”

Christie said he agreed that the border needs to be secured, but the idea that Trump has in mind would not be practical.

“For 15,000 people a day to be deported every day for two years is an undertaking that most almost none of us could accomplish given the current level of funding and the current level of enforcement officers,” Christie said.

Christie said other methods are needed — such as electronics, drones, the FBI and Bureau of Alcohol, Tobacco, Firearms and Explosives, and stricter enforcement of visas.

Bush also took issue with Trump’s plan, and demanded an apology for a remark by Trump suggesting that Bush’s less-draconian views on immigration might be connected to the fact that Bush’s wife is Mexican-American. Bush demanded an apology from Trump, which he refused to issue.

As to Trump’s plan, Bush said, “To build a wall and deport people… would cost billions of dollars, hundreds of billions of dollars. It would destroy community life. It would tear families apart.”

But unlike some of the other candidates, Cruz praised Trump for bringing up the issue.

“I’m very glad that Trump’s being in this race has forced the mainstream media to talk about illegal immigration,” he said.

Neurosurgeon Dr. Ben Carson also took on Trump on the issue of taxation. Trump favors progressive taxation, while Carson favors a flat tax based more on Biblical tithing.

“It’s all about America. You know, the people who say the guy who paid $1 billion because he had $10 (billion), he’s still got $9 billion left. That’s not fair,” Carson said.

But Trump disputed Carson’s claim that a graduated income tax is “socialistic,” and said it is not fair that people making millions or billions end up effectively paying much less than someone making $50,000 a year.

“I know people who are making a tremendous amount of money and paying no taxes, and it’s not fair,” he said.

Meanwhile, Paul also took issue with some candidates’ statements — including Christie’s — that they would enforce the federal laws against marijuana and override the laws in the states that now permit recreational use. He said the drug war overwhelmingly affects the poor.

“We say we like the 10th Amendment until we start talking about this,” he said.

Moderators also noted that Trump had spoken supportively of claims that vaccines are linked to autism. Carson, who had been a pediatric neurosurgeon, said there is no such evidence.

But Trump said he had seen youngsters get sick and then develop autism after receiving vaccines.

“Autism has become an epidemic… it has gotten totally out of control. I am totally in favor of vaccines, but I want smaller doses over a longer period of time,” he said.

Carson replied, “He’s an OK doctor.”

Candidates also discussed at length the question of defunding Planned Parenthood, U.S. Supreme Court appointments, and other issues.

In the first Republican presidential debate, most candidates took a hands-off approach to Trump and hoped the brash billionaire would hurt himself.

Instead, he only got stronger.

The billionaire’s unexpected durability has some of his rivals shifting their strategy for Wednesday’s second showdown. Now their goal is to engage Trump without damaging their own campaigns.

The change reflects an evolution in the way Trump is viewed within the Republican Party. No longer dismissed as a summer fling for frustrated voters, Republicans increasingly see Trump as a candidate who could remain atop the field for months and win some early states.

Trump heads into the second debate Carson, who is climbing in recent polls.

In a new CBS News/New York Times poll out Tuesday, Trump still leads the pack at 27 percent, but Carson is close behind at 23 percent. With his candidacy on the rise, Carson is likely to face heightened scrutiny from debate moderators.

Fiorina is also a political outsider, having spent most of her career in business. She’s also showed no fear in taking on Trump, including after he was recently quoted insulting her appearance. She’s also thrilled GOP audiences with her sharp criticism of Democratic front-runner Hillary Rodham Clinton.

Florida Sen. Marco Rubio, who has largely avoided criticizing his fellow candidates, also doesn’t plan to take on Trump. Rubio’s campaign said the senator didn’t see a need to mix things up like other candidates who are “falling” in the race.

Also on stage was Ohio Gov. John Kasich, who is well-liked among more moderate, business-minded Republicans.

The audience was made up of 400 invited guests.

Four candidates lagging behind in national polls did not qualify for the main event and will be relegated to an earlier debate: Jindal, Pataki, South Carolina Sen. Lindsey Graham, former Pennsylvania Sen. Rick Santorum.

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