By Jon Keller, WBZ-TVBy Jon Keller

BOSTON (CBS) – “We are on the verge of picking someone who cannot do this job,” warned former Ohio Gov. John Kasich at the start of Wendesday’s latest GOP debate, a shot at front-runners Donald Trump and Ben Carson.

That made it clear this would not be a polite affair, and Kasich followed up by mocking Carson’s plan for balancing the budget and ridiculing Trump’s ideas for stemming the flow of illegal immigration.

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The low-key Carson let it pass, but Trump shot back: [Kasich] “was so nice, he was such a nice guy, he said oh, I’m never gonna attack, and then his poll numbers tanked, that’s why he’s on the end [of the debate stage], and he got nasty.”

Another testy moment: former Florida Gov. Jeb Bush hitting Sen. Marco Rubio for missing votes in the Senate. “Marco, when you signed up for this, this was a six-year term, and you should be showing up for work. What is this, like a French work week?”

But Rubio was ready for it, noting other candidates from Barack Obama to John McCain who missed many more votes than he has while running.

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“Someone has convinced you that attacking me is gonna help you,” said Rubio. “My campaign is gonna be about the future of America, it’s not gonna be about attacking anyone else on this stage.”

Round to Rubio. And for Sen. Ted Cruz, perhaps the night’s biggest cheer when he lambasted the CNBC panel for their gotcha questions and intrusive moderation.

“You look at the questions – ‘Donald Trump, are you a comic book villain? Ben Carson, can you do math?’ How about talking about the substantive issues people care about?”

Businesswoman Carly Fiorina gave yet another assured debate performance and NJ Gov. Chris Christie was strong on social security reform.

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But I didn’t see or hear anything likely to change the current polling pecking order.

Jon Keller