Story highlights Donald Trump said as a candidate he'd pull out of the North American Free Trade Agreement

Trump has the authority to unilaterally pull out of NAFTA, congressional sources say

(CNN) Republican leaders worried about President Donald Trump's trade agenda are warning him not to pull out of the North American Free Trade Agreement, saying it could drastically undercut American businesses throughout the country.

In interviews with top Republicans, some are expressing concern about the protectionist views voiced by the new President on the campaign trail and in the very early days of his administration. Many have expressed unease about Trump's call to instate a stiff border tax on companies that ship jobs overseas and his push to pull out of the Trans Pacific Partnership.

But his plans over NAFTA have prompted growing concern, especially if he takes the extra step to pull out of the 23-year-old agreement, a threat he repeated time and again on the campaign trail.

"I don't see any benefit in trying to crawl back into our shell as a country," Senate Majority Whip John Cornyn, a Texas Republican, told CNN. "We won't benefit economically, we're obviously next door to Mexico, as I frequently tell my friends in Mexico, we can't get a divorce. We need to figure out how to make this marriage work."

Utah Sen. Orrin Hatch, chairman of the Senate Finance Committee, which oversees trade laws, issued this blunt warning: "I think we ought to stay in NAFTA. That doesn't mean we can't make better agreements than we have. But I think we ought to do our best to uphold those international trade agreements."

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