COUNCIL BLUFFS, Iowa -- One of the surprising but reliable axioms of the 2016 Republican presidential race has been that Donald Trump can never go too far in his bombastic remarks.

But in Iowa on Sunday, it appeared Gov. Chris Christie -- one of Trump's GOP rivals -- discovered first-hand that even Trump's supporters have their limits.

Addressing Christie, Gary Swanson identified himself as having initially backed Trump. On paper, Swanson seemed to be the perfect match for the tycoon. He's a retired, white, male who is a Vietnam veteran and a retired Iowa state trooper. And Trump had just skipped the seventh GOP debate last week to hold a rival veterans charity event.

But something Trump said last week was the final straw, Swanson told Christie during a town hall at Morningside College.

"Trump said he could shoot someone in the street and not lose a single voter," Swanson said. "But he lost two right then and there," referring to him and his wife.

"Is he really as arrogant, loud-mouthed and self-centered as he seems to be?" continued Swanson, who had postponed attending Sunday worship services to come to Christie's town hall.

The New Jersey governor answered that he'd known Trump for 13 years, and that "if people think that somehow, as president of the United States, he's going to speak differently or act differently, there is nothing in my experience of him that would lead me to believe that."

Still, even Christie admitted he'd been flummoxed by Trump's rise.

"It is almost impossible for me to believe that Iowans -- Iowans -- are going to give Donald Trump the Iowa caucus," continued Christie. "I see the polls. I know, I've seen them, but I just have an impossible time believing" he'd win.

The latest Des Moines Register/Bloomberg poll released on Saturday evening showed that with barely 24 hours left before voting started, U.S. Sen. Ted Cruz of Texas had fallen back into second place, and Trump was again in the lead.

Establishment Republicans like former Gov. Jeb Bush of Florida and Christie are stalled at 2 percent, while U.S. Sen. Marco Rubio, who is trying to woo the GOP establishment, has jumped to third place with 15 percent.

"I can't imagine that man as president of the United States," responded Swanson, referring to Trump, "with all the outrageous things that he has come up with. It's just unbelievable."

"Yeah, you're feeling my pain right now," Christie said.

The crowd broke into laughter.

Two hours later, at a Quaker Steak & Lube in Council Bluffs, it happened again.

Melanie Roll, a 48 year old paramedic who now teaches EMT certification course at Creighton University in nearby Omaha, Neb., told Christie that she would "like to vote for you," but if the governor didn't endure until Nebraska's May primary, "I will vote against (Trump) at all costs."

"How can you guys tell him to go back home?" she asked Christie.

Her question drew laughter and applause from the 150-strong crowd.

"Don't let your heart be troubled," Christie told Roll.

"Anybody who says this race is over, is laughable. Nobody's even voted yet. ... There's lots of primaries to go yet. Iowa's the most important thing -- until next Tuesday, when New Hampshire's the most important thing. And then, after next Tuesday, New Hampshire's the most important thing -- until next Saturday, when South Carolina will be the most important thing."

The governor closed by looking directly across the room into the eyes of the paramedic and promised her: "So, I'll see you in Nebraska in May, don't you worry."

The crowd erupted into laughter and applauded for 12 seconds, and Christie made his exit soon after.

Claude Brodesser-Akner may be reached at cbrodesser@njadvancemedia.com. Follow him on Twitter @ClaudeBrodesser. Find NJ.com Politics on Facebook.