President Donald Trump’s use of a national security law to threaten tariffs on imported cars drew widespread criticism Thursday, including sharp rebukes from senior members of his own Republican Party.

Lawmakers, the auto industry and foreign trade partners were among those lambasting Mr. Trump’s move Wednesday to order a review of imported vehicles and auto parts under Section 232 of the Trade Expansion Act, the same law Mr. Trump used to impose tariffs on imported steel and aluminum in March.

“The president needs to use the national security waiver in ways that I think visibly meet the test,” said Sen. Roy Blunt (R., Mo.). “I didn’t think aluminum and steel met the test. I certainly don’t think automobiles l meet the test.”

The 1962 law gives the White House broad flexibility to impose and adjust tariffs, exempting some trade partners along the way, based on national security concerns. In the cases of steel and aluminum, it has already allowed the administration to gain concessions from countries seeking to avoid U.S. penalties on their products.

The law gives the president wide latitude in defining a threat to national security. That, in turn, allows Mr. Trump to defend the tariffs politically, beat back legal challenges and, at least so far, avoid any major dispute at the World Trade Organization, which regulates global trade.