This month, Mr. Trump refused to spare Europe from his tariffs on steel and aluminum, then used an annual meeting of major democracies to double-down on his clash with allies, enhancing fears of trade conflict.

Gruppo Ventura presents itself as relatively insulated against such shocks, given that the Italian government pays it to service rail tracks — the sort of activity that must continue. Still, company executives are concerned that the cost of rail tracks will climb along with the price of steel.

“Everything is a bit more complicated,” said Gruppo Ventura’s chairwoman, Maria Antonietta Ventura.

All of this has been playing out against the latest outbreak of Italian political drama, which has placed power in the hands of two populist parties, the Five Star Movement and the League. They have promised to deliver tax cuts and a basic income program — unconditional cash grants for all — without elaborating on how they plan to pay for them, creating fresh worries about Italy’s alarming public debt. Their hostility toward the euro, the currency shared by 19 European nations, has reinvigorated concerns about its endurance.

This trifecta of troubles — higher oil prices, American steel tariffs and a crisis of confidence in the government — has turned Italy into a leading export of an unwanted commodity: worry.