Gov. Christie made the morning television rounds Monday, dismissing Republican rival Donald Trump's talk of making Mexico build a border wall, attacking Democrat Hillary Clinton over her use of private e-mails, and laughing off a column that advised him to drop out of the 2016 race.

In an interview on CNN's New Day, Christie said Trump's plan to build a wall along the southern border and have Mexico pay for it "makes no sense."

"This is not negotiation of a real estate deal, okay? This is international diplomacy," Christie said. He called for building a wall along portions of the border – paid for by the United States, he said – and having businesses use the E-verify system. "Make your profit legally," Christie said.

Of another Trump proposal, denying citizenship to babies born in the U.S. to undocumented immigrants, Christie said, "I think it's got to be something that is discussed, but I don't think that's the first thing we should be worried about."

Christie also went after Clinton for her use of a private e-mail address and private server while serving as secretary of state.

"Why did you wipe it clean, Mrs. Clinton? Why?" Christie asked in the CNN interview. He also said there was "ample evidence here to criminally investigate her conduct."

Christie's administration drew scrutiny for using private e-mail addresses in correspondence related to the George Washington Bridge lane closure scandal. The e-mails – including the "Time for some traffic problems in Fort Lee" message sent by a now-fired Christie staffer – were discovered by a legislative subpoena.

"In today's world, everybody has their own private e-mail account," Christie said Monday. But Clinton, he said, "was exclusively using it."

"Can you imagine if after the bridge investigation began, if I came out and said, 'Oh by the way, I've done all of my business as a governor on a private e-mail server, and I've deleted 30,000 of those emails, but trust me, none of it had to do with the bridge'? Give me a break," Christie said.

Phone records subpoenaed by lawmakers last year revealed that 12 text messages between Christie and a top aide, exchanged while lawmakers were hearing testimony related to the bridge scandal, were deleted. Christie said earlier this year he "routinely" deleted text messages.

Christie also faced questions about his lagging position in the polls. A Fox News poll taken after the Aug. 6 debate showed Christie at 3 percent support among likely Republican primary voters, tied with Kentucky Sen. Rand Paul.

Asked on Fox and Friends about a Star-Ledger column headlined "Time to call it a day, Guv," Christie said he was "campaigning hard" in Iowa and New Hampshire. He plans to return to both early-voting states this week.

"I love people who determine an election in August the year before it happens," Christie said.