Paul Ryan led a pack of senior Republican lawmakers in an attack Thursday on the tariff policies of Donald Trump.

House Speaker Ryan said in a statement that he “feared the unintended consequences” of the new tariffs. The statement was issued only moments after President Trump signed proclamations of the new tariffs in a ceremony at the White House.

Ryan was joined by Jeff Flake, the Republican from Arizona, who described the tariffs as “lethal poisons.” Flake said he would introduce legislation to “nullify these tariffs,” a phrase that echoed a fraught period in American history.

In 1832, the state of South Carolina attempted to declare as null and void the federal government’s tariffs, a declaration of a very strong version of states rights that would rear up again when South Carolina led the movement of states to secede from the U.S. during the civil war. That “nullification crisis” was brought to an end by President Andrew Jackson’s declaration of the supremacy of federal law, cementing his place as a hero to American nationalists. President Trump has a portrait of President Jackson in the Oval Office.

Senator Pat Roberts, the Kansas Republican, described the tariffs as a “tax on consumers” in a statement Thursday night.

“The proposed tariffs would nullify the positive gains created by the recent tax reform package passed by Congress,” Roberts said.

The Republicans protesting the tariffs offered no evidence that the tariffs would have negative economic consequences such as raising consumer prices or eliminating jobs. Even among the economists critical of the tariffs, no one has said that the effect of the tariffs would be so strong as to completely counteract the deep tax cuts passed last year.

The Trump administration has insisted that the tariffs will not cost jobs or raise prices. On Thursday, President Trump pointed out that steel and aluminum manufacturers have already announced new investments and new jobs as a result of the tariffs.