TOKYO - The ruling Liberal Democratic Party (LDP) suffered a hammering in a Tokyo assembly election on Sunday (July 2), in a poll that is seen as a referendum on Prime Minister Shinzo Abe and his administration.

It lost to the upstart Tomin First no Kai (Tokyoites First) party, run by Tokyo Governor Yuriko Koike, which together with its allies clinched a majority of 79 seats in the 127-seat assembly. The LDP, which fielded 60 candidates and had 57 members in the former assembly, won only 23 seats.

The LDP's worst showing in the capital had been in 2009, when it won 38 seats.

Mr Abe held a meeting with Finance Minister Taro Aso and Chief Cabinet Secretary Yoshihide Suga on Sunday evening, declining to respond to reporters when asked about the election results.

Defence Minister Tomomi Inada also declined comment. She had come under fire for using the Japan's military Self-Defence Force to lobby for votes for a LDP candidate.

Foreign Minister Fumio Kishida, who leads a different LDP faction from Mr Abe's and who is said to be eyeing the prime minister's role, said on Sunday night: "It is a very tough result for the LDP, and the party must reflect on it seriously. We must make efforts to decide our next steps, so as to win back the trust of the voters one by one."

Mr Hakubun Shimomura, who leads the LDP's Tokyo chapter, said the result was "much more severe than expected". Alluding to the gaffes and scandals that have plagued the party, he said: "There is a sense of distrust towards the LDP in Tokyo, arising from the major headwinds due to national political issues. I humbly take responsibility for this defeat."

He resigned from his position late on Sunday night.

The Tomin First camp, meanwhile, was jubilant. Ms Koike said in her first interviews as results streamed in: "The Tokyo voters have recognised our pledges to achieve policies that serve the good of the people. This is a pivotal moment."

Central to the Tomin First's campaign were policies to weed out wasteful spending and enact laws to curb passive smoking in Tokyo, which is home to 13.7 million people - with some 11 million eligible to vote - and accounts for a fifth of the nation's economy.

These policies resonated with voters, who recall the Olympic Games' ballooning budget under Ms Koike's LDP-approved predecessor.

A national bill on passive smoking, meanwhile, reached an impasse in the Diet - which the LDP controls - as many LDP lawmakers are said to have ties with influential tobacco lobby groups.

The 2009 poll proved to be a harbinger of a national defeat for the LDP when it later ceded majority in the National Diet to the then-Democratic Party of Japan (DPJ), which ruled Japan from 2009 to 2012, breaking the LDP's near-consecutive reign since its formation in 1955.

Mr Abe will need to call a Lower House election by December 2018.

The defeat in Tokyo comes also as the LDP is attempting to revise its post-war Constitution for the first time in 70 years, with opinion polls showing a split populace over changing the supreme law of the land.

The LDP's loss is the culmination of a tumultuous year in politics for the party, which has been seen as evasive in answering to political scandals and complacent in ramming home controversial bills.

Mr Abe has been plagued with allegations in not one, but two, favouritism scandals surrounding educational institutions.

The first was over a sweetheart deal to build an elementary school in Osaka for education operator Moritomo Gakuen, whose license has been suspended. Mr Abe's wife Akie had praised the school's ideologies, despite it having made students recite a pre-war imperial edict every morning.

The second, was over a permit for Kake Gakuen to open Japan's first veterinary school in 52 years in a deregulated zone. Mr Abe allegedly stepped in to expedite the deal because Kake Gakuen is run by a close friend. Top LDP officials - including a former education minister - have been implicated in the scandal.

And in June, Lower House lawmaker Mayuko Toyota resigned after she was caught on tape hitting her male assistant as he was driving, and calling him "baldie".

In the same month, the LDP had come under flak for its so-called "anti-conspiracy" bill whose objective is to deter terrorism and organised crime, but has sparked fears of overreaching government surveillance and a clampdown on civil liberties.

Voter turnout for Sunday's election stood at 51.27 per cent, up 7.77 percentage points from 2013.