WASHINGTON (Reuters) - President Donald Trump's 2024 campaign promise to impose steep tariffs on imports -- including those coming from close U.S. allies -- has some of his fellow Republicans in Congress worried about its potential hit to their home-state economies.

Trump faces a self-imposed Saturday deadline to potentially slap 25% tariffs on imports from Canada and Mexico, as well as increased tariffs on Chinese goods, which could both drive up the cost of imported goods and raise the risk of retaliatory tariffs hitting exports.

Congressional Republicans walked a narrow line in raising concerns about the risks without directly criticizing Trump's decisions.

"I'm not a big fan of across-the-board, universal uniform tariffs because in some cases of the impact it has on the ag community, which is critical to our state," Republican Senate Majority Leader John Thune, who hails from agriculture-rich South Dakota, told Reuters. He noted that the level of tariffs Trump may impose "remains to be seen."

South Dakota is one of 39 U.S. states that count Canada or Mexico as their top export market. Trump won 26 of these states in the 2024 election and 16 of these states each have exports of more than $500 million annually to either Canada or Mexico, which are top two U.S. export markets with a total value of more than $354 billion and $322 billion, respectively, according to a Reuters analysis of U.S. Census Bureau data.

Republican Senator Thom Tillis said Trump should "absolutely" threaten tariffs on Mexico as leverage on efforts to stem the flow of fentanyl and migration, as well as on Canada to increase its defense spending to the North Atlantic Treaty Organization.

But the senator, whose home state of North Carolina exports more than $700 million worth of goods to Canada each year, noted that tariffs can trigger higher prices, saying "you have to be very careful."

Senator Chuck Grassley of Iowa, whose state exports more than $16 billion of agricultural goods annually, said he was taking a "wait-and-see attitude."

"Normally I'd be stronger in my comments because I am a free trader. I used to be in the majority when free trading was a majority of the Congress, but now I am in the minority.'

COLOMBIA THREAT SPARKS WORRIES

One of Grassley's constituents is David Walton, a 59-year-old soybean and corn farmer in Wilton, Iowa. He said in an interview that last weekend was an "emotional rollercoaster" as he watched Trump threaten similar tariffs on Colombia -- and then pull back -- once his immigration demands were agreed to by that country's president. 

"The fact that he threatened Colombia made us sit up and take notice that maybe this is a real thing," said Walton, a political independent. "For those operations that are already in a bit of a financial hardship because of the current agriculture economy, we would lose farmers because of this." 

Other Republican senators have argued that those back home are less worried about the possibility of new Trump tariffs because of their experience with increased Chinese tariffs in the first Trump administration, which eventually led to a $16 billion aid package for impacted farmers in 2019.

Trump's nominee for agriculture secretary, Brooke Rollins, told senators recently that a similar farmer aid plan is under consideration again if the tariffs are implemented, however, additional spending like this could complicate the president's pitch that the tariffs would help pay for reauthorization of the 2017 tax cuts this year.    

"The Republican Party had long stood for free markets and free trade, principles that helped cement America as the world's economic superpower," Republican Senator Rand Paul said, defending the Kentucky bourbon producers and car manufacturers he represents, "Many in my own party seem to have forgotten these lessons."

During Trump's first term, bourbon was one of the U.S. exports to countries including Canada and Britain targeted for retaliatory tariffs.

Senator Jim Justice from West Virginia, whose home state's exports rank 39th among the 50 states, cheered on Trump's tariff plan.

"Everybody runs through the streets saying, 'The sky is falling! The sky is falling!' but it doesn't fall," Justice said.

Top Canadian officials have threatened retaliatory tariffs, but Alberta Premier Danielle Smith, a conservative sympathetic to some of Trump's complaints about U.S.-Canada relations, tried a more diplomatic approach in recent Capitol Hill meetings with multiple Republican senators by leaning into the linked economies.

"We have 34 U.S. states whose principal trade relationship is with Canada. And so those who have that strong relationship, it's not a very hard pitch," Smith said in an interview, "They recognize how important it is and how many jobs are created because of that."