The underlying theme of last week’s IMF/World Bank spring meetings was rising angst over retreating US leadership. The gathering took place shortly after America’s closest allies, led by Britain, spurned a plea from Washington to boycott the China-led Asian Infrastructure Investment Bank. More than 50 countries have signed up. Now the US is in danger of inflicting more damage on itself by shutting down its Export-Import Bank.

The bank’s authorisation expires at the end of June and with it tens of billions of dollars in guarantees for US exporters. Detractors see the bank as a symbol of “crony capitalism” because of its support for companies such as Boeing. They badly misjudge what it does. It gives US companies a modicum of comfort against better subsidised competitors. Closing Exim would be the economic equivalent of unilateral disarmament in a world bristling with nuclear weapons.

Capitol Hill’s latest brinkmanship is ill-timed. In the past two years, Chinese development banks have lent $670bn in subsidised credit to help domestic companies win bids all over the world. This exceeds the combined value of all Exim guarantees since it was set up in the 1930s Depression. Never before has Congress balked at its reauthorisation. Tea Party Republicans say Exim distorts market outcomes at the taxpayer’s expense.