On November 15, barely 10 days after the election of a new US president, the world's leading economies will gather in Washington to discuss the global financial crisis. Although the Group of 20 gathering has been thrown together at short notice, amid inflated talk about constructing a new Bretton Woods agreement to reform global economic governance, it can still play a valuable role.

With goodwill and imagination, the G20 leaders can commit themselves to a co-ordinated, co-operative solution to the financial crisis that, day by day, is sweeping across the developing world. That would be a powerful political response to an immediate problem. The alternative, that countries look out for their own interest while the system falls apart, is too horrible to contemplate.

The financial crisis is now - through a global liquidity crunch and extreme risk aversion among investors - affecting even stable and well-run emerging markets. Recent moves to combat it are substantive steps in the right direction.

The Federal Reserve's decision to extend its currency swap lines to Singapore, South Korea, Mexico and Brazil was a courageous and timely way to support well-run emerging market countries. With its new short-term facility, the International Monetary Fund also seems finally to have found a way to support fundamentally stable economies with temporary liquidity problems.

Authorities need to be careful that helping those inside a charmed circle does not harm those just outside. Intelligent use of traditional IMF lending with appropriate conditions attached - not soft-touch, but not micromanaging - should be able to cope with that. But it will require money, and with the IMF rapidly emptying its arsenal, other donors will have to co-ordinate with the overall effort.

The European Union support for the Hungarian rescue is an example to follow. Yet the really big sources of foreign exchange reserves are not in Europe but Asia, particularly Japan and China, and in the Middle East.

Gordon Brown, the UK prime minister who has been visiting the Gulf for this purpose, has called for such governments to put their foreign exchange reserves to work complementing IMF rescue lending. (Implicitly, of course, Beijing and the oil exporters are already financing a crisis-racked deficit country with a shaky banking system - the US.)

This suggestion might be better coming from someone other than Mr Brown. The UK, backed by France, has spent the past two years dragging its feet in accepting more contributions from emerging Asian nations to the IMF, balking at the increased votes on the fund's executive board that come with them.

To ask Beijing to stump up more cash now without gaining any more say over how it is spent is asking a lot - but Mr Brown may feel, with some justification, that his leadership role in the crisis entitles him to a dose of chutzpah.

The underlying principle is, after all, a good one.

China, despite being left out of some of the key discussions on the global economy - such as the co-ordinated interest rate cut on October 8 - seems to be biting its tongue and playing a remarkably constructive role. It could, for example, easily have single-handedly bailed out Pakistan in return for foreign policy concessions. Instead Beijing seems likely to join an IMF-orchestrated rescue mission.

The G20 meeting will not resolve the intricacies of regulating credit default swaps or introducing new counter-cyclical capital ratios for banks. But it does offer a chance for some of the rich economies to undo some of the damage they have done to global economic co-ordination over the past decade. Determined US leadership for the future will have to wait until a new president moves into the White House in January. The rest of the world cannot allow a vacuum to exist until then.

Back in 1944, it took many months of detailed planning before the articles of association of the IMF were signed in the white-wood, red-roofed Mount Washington hotel at Bretton Woods in New Hampshire. Political leaders at the G20 meeting cannot hope to produce such a blueprint for a new global financial regulatory regime.

The G20 leaders can, however, give marching orders to their civil servants to get going on imagining what the new world might look like. This may take months, even years. Leaders may not have all the answers on November 15, but they do need to show they are ready to act.