Tough debate night for Jeb Bush, Rubio seen getting bump

Opinions on who came out on top at the CNBC GOP presidential debate varied among former politicians and insiders on Thursday, but there was one thing they agreed on: Jeb Bush was not the winner.

"It was a tough night. There's no question about it," Bush supporter Eric Cantor told CNBC's "Squawk Box."

However, the former Republican House majority leader said the debate was not a make-or-break moment for Bush.

Read MoreRepublican debate: Here's who won...and who lost

"Remember, you don't win or lose a campaign in a single debate," he said. "Frankly, he's got the resume and the experience and [he was] the only one on that stage who's got eight years of experience to demonstrate that he can go to Washington and fix Barack Obama's mess."

Democratic former Gov. Jennifer Granholm of Michigan called Bush's performance "lackluster" and "bland."

Bush failed to shine in the moments in which he became combative with other candidates, but fared best in discussions on Medicare and managing his state's finances, said Harold Ford Jr., a former Democratic congressman now with Morgan Stanley.

"The challenge Gov. Bush has is that he is a serious, sober, somber kind of guy. He's not a guy to take someone on," Ford told "Squawk Box." He said the the former Florida governor's in-your-face confrontation with Sen. Marco Rubio about his absences from Capitol Hill fell flat.

Rubio responded by ticking off a series of candidates who had missed votes, including Sen. John McCain, after whom Bush has said he is modeling his campaign.

Read More Jeb Bush to Marco Rubio: You should be showing up to work

A large part of the Republican establishment has not settled around a candidate, Ford said. After the debate, the teams behind Rubio, Ohio Gov. John Kasich, and Sen. Ted Cruz of Texas should be pleased, he added.

Rubio and New Jersey Gov. Chris Christie turned in strong performances at the debate, but the question is whether that will move the chains, former White House aide Joe Watkins told "Squawk Box."

"Doing a great job in the debate and actually moving those numbers up in Iowa and New Hampshire don't always coincide," the former staffer for George H.W. Bush said.

"I wouldn't be surprised to see Marco Rubio see some forward movement in his numbers in the coming week, and maybe a little bit for Christie as well, but mostly Rubio."

Read MoreRubio: Media should be harder on Hillary

As for front-runners Donald Trump and Ben Carson, Watkins said no one knocked either of them off their perch.

Overall, the debate did not provide a defining moment for any of the candidates, said Andrew Card, former White House chief of staff for George W. Bush. But it didn't eliminate anyone either, he told "Squawk Box" on Thursday.

With so many candidates still standing, Card said the race will come down to a ground game in Iowa and New Hampshire, the first states to hold primary votes. Even then, the Republican National Convention may not be much closer to selecting a candidate because those states have not always picked the ultimate nominee in the past, he noted.

"I don't like to say this, but we might be headed to a brokered convention," he said. "We haven't had a brokered convention since 1976."

Read More Candidates' claims: The Fact Patrol reports for duty

The current Republican poll leaders represent a wide spectrum, and that division could work in Democrats' favor, said Thomas McLarty, former White House chief of staff under Bill Clinton.

"Even if a more establishment candidate like a governor ... consolidates, you've still got a pretty divided Republican Party, when you see a pretty unified Democratic Party," he told "Squawk Box."

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