TOKYO - FLAMBOYANT conservative Taro Aso took charge as Japan's new prime minister on Wednesday, pledging to work for a 'cheerful' nation by reviving an economy in the doldrums.

With elections expected within months, Mr Aso started the job with an unusually sombre tone.

He said he would push for emergency measures to revive Asia's largest economy, which contracted in the last quarter.

'To make Japan a cheerful and strong nation ? that is my mission,' Mr Aso said. 'I truly feel the heavy responsibility of being prime minister.'

'I am especially aware of people's worries about the economy, complaints about their everyday lives and distrust of politics,' Mr Aso said.

Mr Aso, 68, was chosen as president of the long ruling Liberal Democratic Party on Monday, and already had begun piecing together a Cabinet expected to include a fellow hawk as finance chief.

The former Olympic sharpshooter was declared premier after the LDP-controlled lower house overruled the upper house, which had voted for Ichiro Ozawa, the chief of the opposition Democratic Party of Japan.

Mr Aso, known for his rightist leanings and acerbic wisecracks, will lead a country wracked by political divisions and spiking concerns over the economy, which has stalled amid the ballooning financial crisis in the United States.

'When I look at the financial situation and other things, I feel like we're in a turbulent period - not in peacetime', Mr Aso told reporters before the vote, referring to the crisis over bad debts hitting global markets.

'Frankly speaking, I am once again feeling the gravity of my responsibilities.'

Mr Aso replaced Mr Yasuo Fukuda, a mild centrist whose ratings dived after he raised medical costs for the elderly.

The ruling Liberal Democratic Party (LDP) picked Mr Aso on Monday as its new leader by an overwhelming majority, placing its trust in a crowd pleasing - though gaffe-prone - campaigner.

Analysts expect him to call a general election as early as late October in a bid to hold off gains by the rising opposition, which has pounded away at the LDP's traditional strongholds in the countryside.

The final battle has begun. The autumn of elections - the autumn to change the government - is coming,' said opposition chief Ichiro Ozawa, whose bloc controls one house of parliament.

The LDP has been in power for all but 10 months since 1955, but Mr Aso will be its fourth prime minister in the past two years as the party struggles over a raft of scandals and, more recently, a faltering economy.

Mr Aso said his first priority would be to pump stimulative spending into the economy, the world's second largest but teetering on the brink of recession, clashing with LDP free-market reformists who in recent years have pushed to tame a ballooning public debt.

Newspapers said Mr Aso would tap as his finance minister Shoichi Nakagawa who, echoing the incoming premier, said he would make 'full use of all sorts of policies' to invigorate the economy'.

Some people label us as freespenders or old-guard cronies as we say we are not hesitant on fiscal spending,' Mr Nakagawa, a former industry minister, wrote in a newspaper column. 'But we do not intend to backtrack on reforms.'

Mr Nakagawa - who was shunned by the more dovish Fukuda - has raised controversy through strong criticism of China and calls for Japan, the only nation to have suffered atomic attack, to study developing nuclear weapons.

This is the lineup aimed at avoiding any political scandals ahead of the imminent general elections,' said Prof Shujiro Kato, professor of politics at Toyo University.'Nobody reported to be appointed as minister is a fresh face.'

Newspapers said the foreign minister would be Mr Fumihiro Nakasone, the son of one of Japan's best-known premiers, Yasuhiro Nakasone, who led Japan in the 1980s and was a close ally in ex-US president Ronald Reagan's anti-communist campaign.

Like Mr Aso, Mr Nakasone was uneasy with some of the free-market reforms during the 2001-2006 premiership of Junichiro Koizumi, who was popular with the public but blamed by some LDP members for alienating rural voters by cutting services.

However, in a bid to ensure party unity, Mr Aso was expected to keep in place Fiscal and Economic Policy Minister Kaoru Yosano, who had challenged him for the top job arguing that Mr Aso's economic policies were irresponsible.

Another rival, Mr Shigeru Ishiba, was tipped to be farm minister, a position that has frequently been hit by scandal.

Mr Ishiba survived resignation calls as he managed crises as Fukuda's defence minister.

Mr Aso promises a return both at home and abroad to some of the more flamboyant ways of Mr Koizumi, who would regale summits by singing Elvis Presley songs, after a two-year gap of drier leaders.

Known for his love of comic books, as foreign minister Aso entertained summits by doing a Humphrey Bogart impersonation and dancing in the costume of a samurai. -- AFP