Tokyo residents went to the polls Sunday in a big test for embattled Prime Minister Shinzo Abe, whose ruling Liberal Democratic Party is facing a powerful challenge from the megacity’s popular governor for control of the local assembly.

Former TV anchorwoman Yuriko Koike, who was elected governor in a landslide last year, is hoping to seize control of the 127-seat Tokyo assembly which currently has a LDP majority.

Koike, who has also served as defence and environment minister, has approval ratings topping 60 percent and is already been spoken of by analysts as a potential future prime minister, as Abe battles a cronyism scandal.

The energetic 64-year-old quit the LDP last month to lead the newly-formed Tomin First no Kai (Tokyo Residents First), and is hoping to take charge of the chamber after forging an alliance with the Komeito party, a Buddhist-backed moderate group that has long sided with Abe in national politics.

Koike has pledged to rein in overspending on the Tokyo 2020 Olympics and has upturned convention by allowing television cameras into what were traditionally closed-door city government meeting.

Many Tokyo residents have applauded her approach to shaking up the conservative local political establishment.

“From what I see, the Tokyo assembly (dominated by the LDP) is seriously old fashioned and needs to change,” said voter Yoshikazu Niwa, 67, who voiced his support for Koike.

A total of 259 candidates are running for seats in the male-dominated chamber that administers a city of nearly 14 million people.

Polls opened at 7:00 am (2200 GMT Saturday) and are scheduled to close at 8:00 pm.

Some 1.36 million Tokyo voters cast ballots before Sunday, significantly higher than the 897,410 voters who voted early in the last poll four years ago, according to the local election commission.

Turnout at 4:00 pm was estimated at 26.10 percent, compared with 23.80 percent at the same stage in the last election, the commission said.

While the vote is local, it is an important indicator of national political sentiment and comes as Abe, who was elected prime minister in late 2012, suffers a series of setbacks.

In the last week, his defence minister Tomomi Inada was in hot water over remarks she made at a local LDP rally. She asked for voters’ support and said it was a request from her ministry and the Self-Defense Forces, Japan’s military.

The SDF is supposed to be politically neutral, and Inada retracted the remark.

Abe, 62, is also under fire over allegations he showed favouritism to a friend in a business deal.

The claims come a few months after the conservative premier was forced to deny he had connections to the controversial director of a school which had purchased government land at a huge discount — and counted Abe’s wife as its honorary principal.

A recent poll by public broadcaster NHK showed Abe’s government had a 48 percent support rating, down three percentage points from a month earlier. His disapproval rating rose six percentage points to 36 percent, the survey showed.

All of the LDP’s 57 candidates won assembly seats in the last city election in 2013 when Abe was riding high in the polls and pushing a plan to kickstart Japan’s long-slumbering economy.