Japan's parliament has elected Yukio Hatoyama prime minister, handing power to an untested government that faces tough economic and social challenges.

日本议会选举鸠山由纪夫为新首相，将权力传授给一个未经任何磨练并面临严峻经济、社会问题的新政府。

The DPJ's victory ended a half-century of LDP dominance

His Democratic Party of Japan won a huge poll victory last month, ending more than 50 years of almost unbroken rule by the Liberal Democratic Party.

Mr Hatoyama said he was excited by the prospect¹ of changing history. "The battle starts now," he said.

The new prime minister's next step is to formally appoint his cabinet.

He has already named former DPJ leader Katsuya Okada as foreign minister, and local reports suggest Hirohisa Fujii has been given the finance portfolio（文件夹，证券投资组合）.

Another former DPJ leader, Naoto Kan, is expected to head a new National Strategy Bureau set up to oversee² the bureaucracy（官僚政治）.

The defeated LDP, meanwhile, will hold an election later this month to choose its new leader, after former Prime Minister Taro³ Aso stepped down.

Domestic focus

The DPJ has entered into a coalition⁴（合并，联合） deal with two smaller parties, the Social Democratic Party and the People's New Party, and controls both houses of parliament.

Its priorities now include tackling a rapidly ageing society and an economy still struggling after a brutal⁵（野蛮的） recession.

The party says it will wrest⁶（夺取，猛抽） control of policy-making decisions from bureaucrats⁷ and deliver more people-centric policies.

It has promised to increase social welfare spending, prioritising（优化） areas such as health and education. It has also promised climate cuts and a foreign policy that is less closely tied to the US.

The DPJ was elected as a wave of discontent with LDP rule swept across Japan.

Professor Phil Deans, from Temple University in Tokyo, said people had become tired of the old system.

"It was extremely effective in developing Japan into a very rich, very important nation," he said, "but it had reached its limits."

Opinion polls have shown many people did not vote for the DPJ because of their policies - but because they wanted change.

Analysts⁸ say the electorate⁹（选民，选区） will be watching the DPJ closely to see if it can deliver.

The BBC's Roland Buerk, in Tokyo, says that in defeating the LDP, Yukio Hatoyama has already achieved what many people thought for years was impossible.

But now the difficult part - governing Japan - begins, our correspondent says.