By Agence France-Presse
Trade officials from Washington and Brussels had continued discussions to find a solution, such as import quotas, that would convince Trump to extend the exemption for the European Union from the 25 percent tariff on steel and 10 percent on aluminum.
But The Wall Street Journal cited people familiar with the matter saying a last minute deal appeared unlikely, and the tariff announcement could come as early as Thursday.
Trump imposed the tariffs in March to address global oversupply of the metals, but though it was largely aimed at China it hit US allies as well.
Washington exempted Canada and Mexico from the tariffs while negotiations continue to revamp the North American Free Trade Agreement, and South Korea agreed to quotas instead of tariffs.
The EU has vowed to hit back at the US with tariffs on American goods, including iconic items such as Harley-Davidson motorbikes, blue jeans and bourbon whiskey.
The metals dispute is just one front in Trump's multi-sided trade confrontation that has hit economic partners and adversaries alike. He has veered from threats to compromise and back again, sowing confusion in global capitals.
He is pressing ahead with 25 percent tariffs on $50 billion in Chinese goods, even after last week saying that dispute was "on hold," and 25 percent tariffs on auto imports, which is likely to spark a fierce reaction from the EU as well.