LAS VEGAS — Jeb Bush came at Donald Trump with everything he had, turning in his strongest debate performance to date just as much of the party was threatening to tune out his flagging candidacy entirely.

He dismissed Trump as a “chaos candidate” who would amount to a “chaos president,” said the billionaire had “crazy” ideas about foreign policy and suggested Trump learned about foreign affairs from the Saturday morning cartoons.


And, two campaign sources say, Bush may be willing to go even further than he did on stage.

Prior to the debate, senior Bush aides began looking into the possibility of making a clear break with Trump — potentially with the candidate stating that, if Trump were the nominee, Bush would not support him.

The former Florida governor didn’t go that far, but the option may still be on the table. The Bush campaign has already examined whether such a statement would disqualify him from certain state primary ballots, some of which demand that candidates sign a loyalty pledge declaring that they will support the eventual Republican Party nominee.

Despite the Las Vegas fireworks, the bout came months too late to be the night’s marquee matchup. Marco Rubio and Ted Cruz proved to be the headliner, with Bush and Trump relegated to second-act status, a sign of the extent to which the race has passed by the son and brother of the past two Republican presidents.

Still, if the Republican Party is searching for an anti-Trump, Bush volunteered for duty. “Others on the stage kind of walked away from that,” said Trent Wisecup, Bush’s director of strategy. “He walked into it.”

Those who’ve been with Bush over the past week say he’s been raring to go. At a Republican Party of Florida event at the Intercontinental Hotel in Tampa last week, Bush went on such an anti-Trump tear that Bush advisers were shocked it didn’t leak. From then on, tackling Trump head-on was the debate game plan — and became a central part of the former Florida governor’s preparations.

Bush has ramped up his rhetoric in private and public since — calling Trump “unhinged” after his plan to bar Muslims from entering the country. At a fundraiser in Las Vegas the day before the debate, Bush previewed for donors his planned aggressive posture, according to one attendee. Talking points circulated to surrogates indicated his plans to take on Trump and emphasize “the need for a commander-in-chief.”

On stage, Bush appeared to relish his aggressive new posture as he talked over Trump. “A little of your own medicine there, Donald,” he said.

Bush brought up more than once Trump’s old comment that he got his information on key issues from “the shows.” “I won't get my information from ‘the shows.’ I don't know if that's Saturday morning or Sunday morning,” Bush mocked. “I don't know which one.”

The renewed aggressiveness helped Bush break into the conversation online. Twitter data showed that Bush accounted for the second-biggest share of the debate conversation (13 percent), after Trump (35 percent). Bush spokesman Tim Miller tweeted that the debate was the best for “website traffic/email sign-ups/donations of any debate.”

And the most talked-about moment on Facebook was the exchange when Bush confronted Trump: “You can’t insult your way to the presidency.”

It was a telling moment, as Trump responded with a dismissive insult. “I'm at 42 [percent], and you're at 3 [percent]. So, so far, I'm doing better,” Trump said.

“Doesn’t matter,” Bush insisted. “Doesn’t matter.”

The question, of course, is whether it does.

“Jeb showed a few signs of life,” said Curt Anderson, who had served as chief strategist for Bobby Jindal’s campaign. “I actually think that Trump had a good debate, marred by his few interactions with Jeb. How odd is that? The very few times Trump stumbled tonight was when Jeb got the best of him. Never could have predicted that.”

If Bush’s interactions with Trump were his strongest moments, his stilted opening and stumbling closing statements served as a reminder for many Republicans of why he had fallen so far and so fast.

“He knocked Trump on his heels a bit, which I give him credit for, but I just think GOP voters aren't buying Bush this year,” said Katie Packer, a Rubio supporter who served as a top official on Mitt Romney’s campaign.

Trump has built such deep goodwill among so many conservative voters, it’s not clear how Bush’s attacks will resonate.

Focus group maestro Frank Luntz suggested Bush fell flat. “The crowd may be applauding, but my focus group is laughing at Jeb. 22 of 26 members said Donald Trump won that exchange,” he tweeted at one point, adding that they used the words "weak," "desperate" and "whiny" to describe Bush. “It's over for him. Sorry,” Luntz wrote.

Even Bush said he didn’t know what was next.

"Look, I don't know the politics of all this. I'm not an expert,” he said on CNN shortly after the debate ended. “I just know sometimes you have to take a stand.”