BRUSSELS, Belgium — The European Union chose Dominique Strauss-Kahn on Tuesday as its candidate to head the International Monetary Fund, putting the former French finance minister in line to take the job in October.

Portugal, which leads talks between all 27 EU nations, said Europe would support Mr. Strauss-Kahn after Spain’s Rodrigo de Rato steps down to spend more time with his family. The IMF board is expected to approve Europe’s choice.

“We think he would be an excellent managing director of the IMF,” the Portuguese finance minister, who led talks between euro nations, Fernando Teixeira dos Santos, said.

Mr. Strauss-Kahn, 58, had previously been expected to challenge unsuccessful French presidential candidate Segolene Royal for the leadership of the Socialist party and turn around the troubled French left.

He said he would now work hard to convince other IMF members that he was the right man for the job.

“The upcoming period should be one of adapting the IMF to the new order created by the globalization of finance,” Mr. Strauss-Kahn said. “The mission of the fund will have to be redefined, as will the respective places of different partners, notably in giving emerging countries the role they are due.”

The French finance minister, Christine Lagarde said Mr. Strauss-Kahn’s international experience helped him swiftly win support from other EU nations. Germany’s Peer Steinbrueck said he was “the best candidate Europe had to offer.”

Europe and America have divided the top jobs at the two major financial institutions, with the EU picking the head of the IMF and America choosing who should lead the World Bank.

But the British finance minister, Alistair Darling, said it was time for the system to change and the post should still be open to candidates from other parts of the world.

“We think there needs to be an opportunity for all members of the IMF to make their own assessment as to individual candidates … and then, of course, pick the best candidate for the job,” he told reporters.

“We don’t believe that the situation whereby it is assumed that there will automatically be a European candidate for the IMF just as there is an American candidate for the World Bank is sustainable in the long term.”

He said Britain would have liked more time to select someone although he described Mr. Strauss-Kahn as a “credible” candidate.

The Dutch finance minister, Wouter Bos, earlier said it was still an “open race” between Europe and candidates from other parts of the world.

Mr. Teixeira dos Santos of Portugal said there was nothing to prevent another candidate from coming forward but that any wider changes should be part of reforms to national voting weights at the IMF and to governance at both the IMF and the World Bank.

Ms. Lagarde said questioning how the IMF candidate is selected should also mean challenging the American role in picking the World Bank president. Europeans were unhappy at Paul Wolfowitz’ slowness to heed calls to resign from the bank following an ethics scandal.

“If this tradition is questioned, it should be for the two institutions at the same time,” she said. “Every candidate from every institution will be open to hearing every concern from developing countries.”

Her German colleague made similar comments.

“After the U.S. could propose the successor for Wolfowitz at the World Bank, I think the current tradition should continue,” Mr. Steinbrueck said.

French President Nicolas Sarkozy had canvassed America and other European countries for their support for Mr. Strauss-Kahn — even though the Socialist earlier said it would be a “betrayal” for him to join Mr. Sarkozy’s new government.

Mr. Sarkozy was more generous.

“He is France’s candidate, but I hope he will be Europe’s candidate,” he said.

Mr. Strauss-Kahn thanked him on Tuesday, saying support from Mr. Sarkozy and the Luxembourg prime minister, Jean-Claude Juncker — a governor of the IMF — had been decisive in winning EU-wide support for his nomination.