Story highlights Kaine hit Trump for his immigration policy

Kaine also defended the Clinton campaign's lack of press availability

(CNN) Democratic vice presidential nominee Tim Kaine said Thursday Donald Trump's trip to Mexico was a "photo op fly-by" and said he thinks "it shows that diplomacy is not for amateurs."

Kaine was in full attack-dog mode during a series of television interviews, mocking Trump's high-profile meeting with Mexican President Enrique Peña Nieto on CNN's "New Day." He also criticized Trump for giving a more moderate immigration message to the Mexican leader, before delivering a fiery speech hours later to an American audience.

"Donald Trump did a kind of photo op fly-by, where he didn't even have the nerve at the last minute to bring up this issue about the wall," Kaine told CNN's Chris Cuomo. "This is the central piece of his campaign -- immigration and deportation, and we're going to build a wall and make Mexico pay for it. But when he looked President Peña Nieto in the eye, he couldn't even bring that up."

Trump said Wednesday that the payment for the proposed border wall didn't come up during his meeting with Peña Nieto, but the Mexican president disputed that assertion.

"That was a choke, and I think it shows that diplomacy is not for amateurs. Donald Trump's an amateur," he added.

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