ATLANTIC — Republican Senator Joni Ernst warns the escalating tariffs President Trump is threatening to impose on Mexican imports would derail the U.S. Mexico Canada Agreement.

“Tariffs cannot be the answer to everything,” Ernst said Friday afternoon during an event in Atlantic. “I think we need to get the trade deal done and then let’s focus on other methods of moving forward with Mexico.”

Ernst, in a written statement released at 6 a.m. today, said Mexico must “step up and do its part” to stop the “stream” of asylum seekers crossing into the United States, but she said the livelihoods of Iowa farmers and producers are at stake if the president imposes new tariffs on Mexico.

“I’m not supportive of the threat of additional tariffs,” Ernst said while attending the grand opening of an ethanol plant. “I say: ‘Let’s get the trade deal done, then let’s work with Mexico to solve this issue.”

Mexico and Canada are Iowa’s top export markets and Ernst says ratification of the USMCA would provide “much-needed certainty” in the ag economy.

“Our farmers are counting on this,” she said.

Iowa’s other Republican senator, Chuck Grassley, has also said new tariffs on Mexico would “seriously jeopardize passage” of the trade deal with America’s North American partners. Grassley said in a statement Thursday night that Trump’s tariff threat toward Mexico was “a misuse of presidential authority and counter to congressional intent.”

Republican Governor Kim Reynolds, who attended the same event in Atlantic today, said the nation’s southern border needs to be secured, but she said “it cannot be done on the backs of Iowa farmers.” Reynolds told reporters she hopes Trump will “rethink” imposing new tariffs on Mexico — or the new trade agreement is endangered.

“We’re at a critical time right now and it’s time sensitive,” Reynolds said. “I was so happy when we finally got the negotiation done to create the USMCA and now we need congress to ratify it.”

President Trump’s top trade negotiator sent a formal letter to congress yesterday signalling the Trump Administration will formally submit the USMCA to congress within 30 days. Officials in Canada took a formal step earlier this week toward ratifying the agreement, but that was before the president threatened new tariffs on Mexico, the other party to the deal.