THE world’s most ambitious free-trade deal in decades is all but dead. Donald Trump has said that on his first day in office America will quit the Trans-Pacific Partnership (TPP), a pact that was nearly a decade in the works. Encompassing 12 Pacific Rim countries, including America, Japan and Canada, the TPP would have covered nearly two-fifths of the global economy. Mr Trump had called it a “horrible deal” on the campaign trail. In declaring his intent this week to withdraw from it, he said it was “a potential disaster for our country”. But proponents say it would have been a big improvement on existing trade deals and very good for America. Which view is right, and what happens now?

Measuring the precise impact of trade deals that have been in place for years is hard enough. Forecasting the impact of future deals is even harder. Nevertheless, many economists would agree with two general statements. On one hand, TPP would have generated more growth for all inside the agreement. A series of independent studies predicted that America would have reaped the biggest gains in dollar terms and that emerging markets, especially Vietnam, would have benefited most relative to their size. On the other hand, while free-trade deals enrich countries in general, downsides can be severe for industries and regions that lose out. Moreover, recent research has showed that these negative effects are often longer lasting than optimists had once believed. The TPP would, in other words, probably have increased America’s growth, but at least some people would have been justified in thinking it horrible.

But looking at the impact on GDP alone is too narrow. The purpose of the TPP was always partly strategic. America and others alongside it, from Australia to Singapore, hoped the deal would let them shape the architecture of international trade in Asia and beyond. Their ambition was that the TPP would set a new standard for future deals. Rather than a traditional emphasis on cutting tariffs (which are already very low between richer countries), they turned to thornier issues such as differences in intellectual-property regulations. Even if the TPP failed to live up to their lofty rhetoric, it did break new ground. It contained stronger protection for labour rights, more environmental safeguards and, for the first time ever, measures to limit government support for state-owned companies. The deal was most notable, though, for its exclusion of China. The door might eventually have been opened to it but only after signing on to the full body of rules that the original TPP members, led by America, had hammered out.

The collapse of the TPP thus creates a void in Asia. America’s role as an economic power in the region has been undermined by Mr Trump’s isolationist turn. In theory the remaining 11 members could refashion the TPP, but Shinzo Abe, Japan’s prime minister, spoke for many in saying that it would be “meaningless” without America. Observers are now looking for China to assume the mantle of economic leadership in Asia. Conveniently, it is pushing for a free-trade deal (the Regional Comprehensive Economic Partnership) that is close to completion. But the shift of power to China is far from straightforward. Countries in the region are wary of its export juggernaut, an awkward starting point at the negotiating table. China’s blueprints for trade deals are also much more conservative than America’s, barely touching the regulatory thicket that made the TPP important. Asian countries will instead need to turn to the messy work of building up bilateral agreements. The hole left by America’s withdrawal is a big one, and not easily filled.