A candidate from Prime Minister Fumio Kishida's Liberal Democratic Party won a House of Councilors by-election Sunday in the conservative stronghold of Ishikawa Prefecture, projections by Kyodo News show.

The result could give momentum to the ruling bloc in the run-up to this summer's Upper House election. But Kishida is also expected to continue facing challenges including the Russian war on Ukraine, which has impacted the nascent recovery of the Japanese economy from the coronavirus pandemic.

Shuji Miyamoto, also backed by the LDP's junior coalition partner Komeito, beat three opposition candidates in the by-election. The 51-year-old had given up his Upper House seat under proportional representation to run for the constituency.

The by-election was held after an LDP lawmaker quit to run in last month's gubernatorial race in Ishikawa, in which votes for the party were divided between three candidates, raising concerns about its unity.

Sunday's victory for the ruling coalition was also helped by opposition parties failing to field a unified candidate, as they are struggling to overcome differences in order to forge a common front against the coalition in this summer's election.