Prime Minister Shinzo Abe was getting down to a second consecutive term in office Monday after a thumping election win, with analysts warning he needed to make good on his promise to fix Japan's economy.

His ruling Liberal Democratic Party (LDP) and its junior partner Komeito swept the ballot on Sunday, with an unassailable two-thirds majority in the lower house of parliament, giving them the power to override the upper chamber.

The coalition won a combined 326 of the 475 seats, crushing the main opposition Democratic Party of Japan, whose slightly improved tally of 73 did not include its leader.

Reports said Banri Kaieda would resign as head of the Democratic Party of Japan later Monday.

Abe, 60, is expected to reappoint exactly the same cabinet after he is formally named prime minister again by the lower house on December 24.

Speaking as the scale of his victory became apparent, Abe signalled he would look to realising conservative dreams like revamping the pacifist constitution and urging a more sympathetic view of Japan's warring past.

"A revision of the constitution is the LDP's long-cherished wish," Abe told an interviewer late Sunday.

"I want to make an effort to enhance the public's understanding of the need for revision," he said.

Shinichi Nishikawa, professor of politics at Meiji University in Tokyo, said: "Prime Minister Abe can focus on whatever he wants to do, including changing the constitution. It appears that no one can stop him."

Abe stormed to power in 2012 on a promise of competence and a pledge to revive the animal spirits of Japan's flagging economy.

His signature "Abenomics" plan was sketched out as a three-pronged strategy involving monetary easing, government spending and structural reforms to cut the red tape that binds the economy.

The printing presses at the Bank of Japan have run hot ever since, pushing the value of the yen down -- to the delight of exporters -- and giving the stock market a huge boost, as stimulus programmes have provided an economic shot in the arm.

But Abe has shied away from the tough reforms that economists say are vital if Japan is to get back on a firm footing -- employment deregulation and tackling the entrenched interests of the agriculture lobby.

- Economy promise -

The prime minister, who had billed the election as a referendum on Abenomics, pledged Sunday to continue his focus on the economy, which he said would remain his "top priority".

"The economy will pick up without a doubt if we continue the current policies," he said.

Commentators said he would be wise to cleave to that promise.

"The election result is an endorsement of the past, not the future," said Hideo Kumano, chief economist at Dai-ichi Life Research institute.

"From now on, he has to show results in line with his promises," Kumano said. "If he fails to improve the economy, his political capital will be reduced easily. A crucial phase is still ahead."

The Mainichi Shimbun, a daily, was among the voices noting that the record low turnout of around 52 percent, diminished Abe's claim to a free hand.

On the diplomatic front, the election victory may temper frayed relations with China, who now know they have to continue dealing with a man they have painted as a dangerous revisionist.

Relations began to thaw last month with a summit after more than two years of chill, which Beijing blamed on Abe's provocative nationalism, including a visit to a war shrine and equivocations on Japan's wartime record of enslaving women for sex.

Masaru Kohno, a politics professor at Waseda University in Tokyo, said despite his professed desire to retell the history of Japan's aggressive warring -- an instinct largely unshared by the Japanese public -- Abe would be pragmatic.

"Many of the issues Japan is facing such as depopulation and women's advancement should be resolved with liberal policies," he said.

"I don't think the election result will herald another era of conservative politics in Japan."