President-elect Donald J. Trump’s threats of tariffs on allies and adversaries alike have unsettled companies and governments across Europe, setting off a scramble for what they fear could be a trans-Atlantic trade war.

Their nascent plans, including a closely guarded effort at the top levels of the European Commission, appear to be more proactive than what they were the first time Mr. Trump took office. But any attempt to form a united front on trade could be hampered by the sclerotic politics across much of Europe.

The French and German governments both collapsed this month. Austria and Belgium are struggling to form governing coalitions long after their most recent elections.

And no clear consensus has emerged on how to respond to whatever Mr. Trump might have in store. Divisions are already emerging between officials who favor a strategy of retaliation if he tries to impose new taxes on European exports and those who favor negotiation.

In a post on Truth Social early Friday, Mr. Trump said he had “told the European Union that they must make up their tremendous deficit with the United States by the large scale purchase of our oil and gas. Otherwise, it is TARIFFS all the way!!!”