By Linda Sieg and Kaori Kaneko
TOKYO (Reuters) - Japanese Prime Minister Shinzo Abe said on Monday he will work to regain public trust after his party suffered an historic defeat in an election in the nation's capital, signalling trouble ahead for the premier amid tumbling support rates.
The dismal showing for Abe's Liberal Democratic Party (LDP) in Sunday's Tokyo Metropolitan assembly election was a stinging rebuke for his 4-1/2-year-old administration, although on the surface it was a referendum on popular Governor Yuriko Koike's year in office.
Koike's novice Tokyo Citizens First party and its allies, including the LDP's national-level coalition partner, the Komeito, took 79 seats in the 127-member chamber.
The LDP won a mere 23 seats, less than half its pre-election total and its worst-ever result in a Tokyo poll.
"I want to regain the people's trust by unifying the party and ... showing results," Abe told reporters.
"It was a severe judgement suggesting (voters) thought the Abe administration was getting slack," Abe said. "We must accept this firmly and seriously and make every effort to return to our original aspirations of when we regained power."
Past Tokyo elections have been bellwethers for national trends. A 2009 Tokyo poll in which the LDP won just 38 seats was followed by its defeat in a general election that year, although this time no lower house poll need be held until late 2018.
Koike, a media-savvy ex-defence minister and former LDP member, took office a year ago as the first female governor in the capital, defying the local LDP chapter to run and promising to reform governance of a megacity with a population of 13.7 million and an economy bigger than the Netherlands'.
The LDP has been hit by a scandal over suspicions - denied by the premier - that Abe helped a friend's business get favoured treatment.
It has also been hurt by cabinet minister gaffes, and by a perception among many voters that Abe's administration has grown arrogant after more than four years in power.
BLACK EYE FOR ABE
The huge victory for Koike's party and its allies has sparked fresh speculation that she will take her party national, but any bid by Koike herself for the country's top job looks unlikely until after the Tokyo 2020 Olympics - if her popularity remains high and her party proves it is able to govern.
"This was less a vote for 'Tomin First' (Tokyo Citizens First) than a repudiation of Abe," said Jeffrey Kingston, director of Asia studies at Temple University's Japan campus. "It was not a grass roots firestorm."
Abe's support rate, which tumbled in surveys last month, slipped again to 38 percent from 41 percent in an Asahi newspaper poll conducted at the weekend. That was lower than the 42 percent who did not back his cabinet.
Abe will likely reshuffle his Cabinet to try to repair his battered image, although the tactic has backfired in the past when new ministers became involved in scandals or committed gaffes.
"The good scenario for the economy and markets is that the Tokyo Assembly election result triggers a pro-reform Cabinet reshuffle, and returns focus to economic issues," wrote Morgan Stanley MUFG Securities' economist Robert Feldman.
"The bad scenario is the LDP becomes paralysed, and few reform actions are taken," he said.
The LDP's poor result could also boost Abe's inclination to delay yet again an unpopular rise in the national sales tax to 10 percent scheduled for 2019. A decision needs to be made around the middle of next year.
It could also affect his push to revise the pacifist Article 9 of the post-war, U.S.-drafted constitution, a politically divisive goal that Abe said in May he wanted to achieve by 2020. "I don't think that will go as planned," said Atsuo Ito, an independent political analyst and author.
Abe had been considered on track for a third three-year term when his tenure as LDP president ends in September 2018, but his sliding ratings and the election loss have clouded that outlook.
"A lot can happen between now and 2018. Two months ago, it looked like he'd waltz to a third term. Now it's uncertain," Kingston said.
(Reporting by William Mallard and Kaori Kaneko; Writing by Linda Sieg; Editing by Paul Tait)