(CNN) Lawmakers from both parties are bracing for a final report from President Donald Trump's Department of Commerce on whether imports of automobiles and auto parts threaten national security.

The findings and recommendations of the probe launched last May are due by February 17, but they could be sent to the White House as soon as Friday -- although the administration may choose not to make the document public right away. Trump, who has threatened to slap tariffs of up to 25% on cars coming from Europe and elsewhere, will have 90 days to decide how to proceed, but he could act at any point once he receives the report.

Senate Finance Committee Chairman Chuck Grassley warned Trump against pursuing tariffs in a floor speech Thursday, pointing to the potential for lost jobs and price increases for American consumers.

"I agree with the President that we must have fair and enforceable trade agreements that benefit Americans," said the Iowa Republican. "Sometimes we have to make hard decisions in order to get there. But I do not agree that we should alienate our allies or jeopardize the health of our own economy to achieve good outcomes."

Trump used the same Cold War-era authority last spring to impose tariffs of 25% and 10% on foreign steel and aluminum, claiming they would act as a useful negotiating tool in various trade negotiations. A bipartisan group of legislators argues Trump has abused the national security purpose of the provision, applying it to imports that don't actually represent a threat.

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