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 tariffs with Ms Malmstrom ahead of a midnight deadline (0500 BST Tuesday), has indicated some US allies will be given last-minute exemptions if they accept a quota of US imports, but not all.