President Donald Trump on Thursday announced new tariffs on imports of steel and aluminum, setting off a firestorm among Republicans.

Sen. Ben Sasse called the move "a massive tax increase on American families."

Conservative policy groups also came out against the move.

Republicans and conservative groups were furious with President Donald Trump's Thursday's announcement that the US would impose new tariffs — taxes on imports — of 25% for steel and 10% for aluminum.

The move is designed to boost domestic production of US metals, but economists, lawmakers, and even many White House officials are worried it could lead to devastating consequences for the US economy.

In response, several Republicans painted Trump's announcement as a grave mistake.

"Let's be clear: The President is proposing a massive tax increase on American families," Sen. Ben Sasse of Nebraska said in a statement. "Protectionism is weak, not strong. You'd expect a policy this bad from a leftist administration, not a supposedly Republican one."

Sen. Orrin Hatch of Utah, a key figure in the passage of the North American Free Trade Agreement who supports free-trade policies, also urged Trump to reconsider.

"Tariffs on steel and aluminum are a tax hike the American people don't need and can't afford," Hatch said in a statement. "I encourage the president to carefully consider all of the implications of raising the cost of steel and aluminum on American manufacturers and consumers."

Sen. John Cornyn of Texas, the second-highest-ranking member of the Republican Senate leadership, told Business Insider that the move was coming from a good place but could lead to negative outcomes such as a trade war.

"Obviously we don't want to be taken advantage of by our trading partners, but then there is always a danger of retaliation and creating trade wars," Cornyn said. "So it's a very delicate balance."

Cornyn also said that while senators knew the decision was "imminent," the announcement on Thursday was unexpected.

Sen. Pat Roberts of Kansas, the head of the agriculture committee, told CNN that the move would be likely to lead to retaliation against American farmers.

"Every time you do this, you get a retaliation, and agriculture is the No. 1 target," Roberts said. "I think this is terribly counterproductive for the ag economy, and I'm not very happy."

In addition to lawmakers, conservative action groups joined the pile-on. Adam Brandon, the president of FreedomWorks, said the decision could reverse economic gains from the new GOP tax law.

"The Trump administration would mar its otherwise strong economic record by imposing these tariffs," Brandon said in a statement. "These could be a lethal blow to all the economic success this administration has ushered in. Higher costs to producers and distributors of goods always get passed on to us, the consumers."

Joe Perticone contributed reporting.