Voting began Sunday in Japan’s House of Representatives election, in which the ruling coalition of Prime Minister Shinzo Abe is expected to achieve a solid victory in the face of a divided opposition.

Recent opinion polls have suggested the coalition of the Liberal Democratic Party and Komeito will maintain a comfortable majority in the Lower House. The ruling bloc is likely to capitalize on the win by pressing ahead with debate on the Constitution’s first amendment ever.

A robust performance could also reinforce Abe’s chances of success in an LDP leadership contest next September.

The opposition vote looks likely to be split between two parties that emerged in recent weeks out of the husk of the collapsing Democratic Party.

Tokyo Gov. Yuriko Koike’s Kibo no To (Party of Hope) has taken on much of the Democratic Party’s conservative wing, while the Constitutional Democratic Party of Japan has absorbed the liberals.

Neither party has had the time or resources to put up candidates in all of the 289 single-seat electoral districts.

Low voter turnout is also expected to work in the ruling coalition’s favor, with rain and wind from Typhoon Lan battering much of the country. Packing winds of up to 252 kilometers per hour (157 mph), Lan lay east of Okinawa on Sunday morning and was expected to reach the Tokyo area early Monday. The season’s 21st typhoon was expected to bring heavy rains in wide areas of the nation, and the Meteorological Agency warned of mudslides and swollen rivers.

Polling stations will close at 8 p.m., with the final result expected by early Monday.

A total of 1,180 candidates are vying for the Lower House’s 465 seats, 289 of which represent single-seat electoral districts. The remaining 176 are filled through proportional representation, based on voters’ preferred parties across 11 regional blocks.

Electoral reforms have reduced the size of the Lower House to a postwar low. It had 475 seats before it was dissolved, with 287 occupied by the LDP and 35 by Komeito.

As part of its election platform, the LDP said it will include in forthcoming debate on constitutional reform the idea of adding an explicit mention of the Self-Defense Forces. The status of the SDF under the Constitution is debated, since Article 9 renounces war and the maintenance of “war potential.”

A two-thirds majority in both Diet houses is needed to formally propose a constitutional amendment, which must then gain a majority of votes in a national referendum.

Dissolving the Lower House on Sept. 28, Abe said he needed to secure a fresh mandate from the public for his administration’s plans for the revenue from a consumption tax increase in October 2019 and for its handling of the threat from North Korea.

But the move appeared timed to take advantage of disarray among the opposition. It also allowed Abe to shelve a fall parliamentary session that would have seen him questioned again about cronyism allegations that have damaged his brand this year.

Koike, who broke from the LDP to run for governor last year, threw a wrench in the works by establishing a “reform conservative” party that she said would aim to topple the Abe administration.

But an initial flash of excitement over Kibo no To has faded in the weeks since, not least because Koike refused to resign as governor to run for the Lower House, leaving her party without a clear choice for prime minister in the event it forms a government.

Koike’s party is pledging to freeze the consumption tax increase and abandon nuclear power by 2030. It is open to including the question of the SDF in debates on constitutional amendments.

The CDPJ, led by former Chief Cabinet Secretary Yukio Edano, was formed after Koike rejected the Democratic Party’s liberal members.

It wants to roll back the Abe administration’s controversial laws on national security and argues that the SDF’s status should not be included in an amended Constitution as long as that “unconstitutional” legislation remains in force.

Over the course of the official campaign, which began on Oct. 10, the CDPJ has increased its share of support in opinion polls but Kibo no To has failed to pick up steam.

Sunday’s election is the first Lower House race in which 18- and 19-year-olds can vote, under a change in the law that took effect last year.