(Bloomberg) -- Prime Minister Fumio Kishida’s ruling party eked out wins in four of five Japanese by-elections held Sunday, public broadcaster NHK said, with the results seen as key to his decision on election timing.

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The premier’s Liberal Democratic Party kept the three seats it previously held of the five, including the constituency in the southwestern prefecture of Yamaguchi vacated when former Prime Minister Shinzo Abe was assassinated last year. It also picked up a fourth, an upper house seat in Oita Prefecture, NHK said, citing exit polling.

The victories will further fuel speculation that Kishida may opt for a national election after hosting the Group of Seven summit May 19-21 in Hiroshima. Still, four of the races had been to close to call earlier and the LDP eventually won three of them with slim margins.

An early general election would play into monetary policy, as the Bank of Japan would face pressure to avoid any changes during the campaign that could disrupt markets.

While Japan’s lower house term doesn’t end until 2025, renewing his mandate could help Kishida keep his party in line as he negotiates a series of difficult policy decisions. Among them are how the deeply indebted country will fund a pledged 60% increase in defense spending amid rising regional threats, as well as a planned doubling of outlays on children and families intended to stem a fall in the nation’s birthrate.

Support for Kishida’s cabinet has recovered in recent weeks, helped by his visit to Ukraine last month as well as progress toward a rapprochement with South Korea. His decision to carry on campaigning after an attempted pipe-bomb attack a week ago as he was about to speak in support of a candidate in Wakayama also nudged him higher in media polls.

--With assistance from Akiko Nishimae.

(Updates with latest results.)

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