Trump was the center of attention right from the get-go at the Reagan Library in Simi Valley, California, with moderator Jake Tapper asking his opponents to comment on whether the candidate should be trusted with nuclear codes if elected.

Several of the candidates promptly took the opportunity to take a swipe at the reality TV star. “Do we want someone with this kind of … careless language to be negotiating with Iran?,” Kentucky Sen. Rand Paul asked, also criticizing Trump for singling out people for their physical looks.

“I never attacked him on his looks,” Trump fired back, “and believe me, there’s plenty of subject matter.”

Wisconsin Gov. Scott Walker, meanwhile, took a shot of his own —”We don’t need an Apprentice in the White House. We have one right now” — only to be attacked by Trump for his low poll ratings.

But former Hewlett Packard chief executive Carly Fiorina got in perhaps the most meaningful jab. Invited to respond to Trump’s critical remarks, in a Rolling Stone interview, about her appearance — remarks that Trump has said were in reference to her persona — Fiorina said: “I think women all over this country heard very clearly what Mr Trump said,” to sustained applause. Trump could only reply that he thought Fiorina was “very beautiful.”

Former Florida Gov. Jeb Bush, one of Trump’s closest rivals, bickered with the real estate magnate over Florida’s refusal to approve casino gambling — something Bush said Trump had pushed for, but Trump denied. “More energy tonight, I like that,” Trump smirked at one point.

The debate focused on foreign policy early on. Several of the candidates condemned the nuclear deal with Iran promoted by President Barack Obama but opposed by a majority of Republicans and some Democrats.

Texas Sen. Ted Cruz expressed his anger at the folly of negotiating with Iran’s leaders. “If I’m president no theocratic Ayatollah who chants ‘death to America’ would ever be allowed to get a nuclear weapon,” he said.

Only Ohio Gov. John Kasich defended the attempt to build an international coalition to prevent Iran from getting the bomb. “We can project across this globe with unity, not just do it alone,” he said.

Trump touted his ability to build relationships with world leaders, both friends and perceived foes. “I would get along, I think, with Putin,” he said. “Between that, Ukraine and all the other problems, we wouldn’t have the kind of problems we have right now.”

On domestic issues, the candidates broadly espoused pro-life views and castigated Planned Parenthood, the federally-funded women’s health provider that has been criticized over a series of videos released by conservative activists purporting to show the illegal sale of aborted fetuses — and Congress, for its inability to defund the group.

Cruz said Planned Parenthood was an “ongoing criminal enterprise” while Christie turned the heat on Democratic Presidential frontrunner Hillary Clinton as being in favor of the “systemic murder” of aborted fetuses. Fiorina got a round of applause condemning videos that, she said, showed people attempting to “harvest [the] brain” of an unborn child.

The evening began with each candidate introducing themselves to the television audience. Former Arkansas Gov. Mike Huckabee took a jab at Clinton and described Trump as the “Mr T” of the race, willing to call anyone a “fool.” Florida Sen. Marco Rubio, meanwhile, made a self-deprecating joke about remembering to bring water — a reference to hisdry-mouthed performance in the GOP’s response to President Obama’s State of the Union address in 2013.

Earlier in the evening, lower-polling candidates sparred in the so-called “undercard” debate. South Carolina Sen. Lindsey Graham was judged to have excelled over fellow candidates Lousiana Gov. Bobby Jindal, former Pennsylvania Sen. Rick Santorum and former New York Gov. George Pataki in the debate, touting his ability to bring parties together by pledging to “drink more” with them on his first day in office.