Opposition parties prepared Wednesday to pass a resolution ousting a senior Liberal Democratic Party lawmaker as head of an Upper House committee, setting the stage for a showdown with the ruling bloc before the Upper House election in July.

If passed, it would mark the first time a committee chair has been dismissed. The LDP lacks an overriding two-thirds majority in the chamber.

The seven opposition parties, including the Democratic Party of Japan, Your Party and Nippon Ishin no Kai (Japan Restoration Party), submitted the resolution Tuesday to sack Yoriko Kawaguchi of the LDP as the head of the Upper House Environment Committee for failing to get permission from the Diet to extend a trip to China by one day. Her absence forced the committee to cancel a session scheduled for April 25.