EU Trade Commissioner Cecilia Malmstrom is to hold last-ditch talks with her US counterpart aimed at exempting the 28-nation bloc from President Donald Trump’s steel and aluminium tariffs.
The EU says it expects a “permanent and unconditional” exemption to replace a temporary measure that runs out on 1 May.
If that fails, it will launch a series of countermeasures.
Germany’s Angela Merkel met Mr Trump on Friday but no breakthrough was reached.
“For the time being our priority is the ongoing high-level dialogue to secure a permanent exemption,” the trade commissioner said, appealing for the EU and US to work together.
A European Commission spokesman said on Monday that the EU was “patient but also prepared”.
US Commerce Secretary Wilbur Ross, who will discuss the deadline of midnight in Washington DC with Ms Malmstrom on Monday, has indicated some US allies will be given last-minute exemptions if they accept a quota of US imports, but not all.