AP
Republican presidential candidate Donald Trump waves to supporters after speaking at a campaign event in Dallas, Monday, Sept. 14, 2015.
Ahead of the second Republican debate in Simi Valley, California, on Wednesday, Republican pollster Frank Luntz told Business Insider that the only one way that Trump can lose support is if he forgoes his outspoken style. It's an outcome that Luntz doubts.
"The key to Donald Trump's success is authenticity. The moment he comes across as the other candidates, the moment that he comes across as a professional politician, is the beginning of the end for him," Luntz told Business Insider. "Even if he's saying things that shock people, that's part of the Trump brand.
Asked about what the likelihood of that would be, Luntz smiled and shook his head.
"He's uncontrollable, he's ungovernable. Donald Trump is like America: ungovernable," Luntz said.
After conducting several focus groups with Trump supporters last month, Luntz said that the unwavering support for Trump left his legs "shaking."
"This is a different cat. This is a different phenomenon," Luntz told reporters after conducting a focus group in Washington, DC, last month.
"This is real. I'm having trouble processing it. Like, my legs are shaking," he added. "I want to put the Republican leadership behind this mirror and let them see. They need to wake up. They don't realize how the grassroots have abandoned them. Donald Trump is punishment to a Republican elite that wasn't listening to their grassroots."
The strength of Trump's supporters is likely to be tested at Wednesday's debate.
Several candidates, including former Florida Gov. Jeb Bush (R) and Sen. Rand Paul (R-Kentucky) have said that they plan to target Trump specifically.
"I think he deserves both barrels," Paul said, according to the The Daily Caller. "I want to make sure everyone in the whole country knows he's a fake conservative."