OSAKA — Lower House member Kiyomi Tsujimoto resigned Tuesday from the Social Democratic Party over the SDP's exit from the ruling bloc amid the Futenma base row and after its poor showing in the July 11 Upper House election.

Indicating she will become an independent, the SDP stalwart said about her exit that politicians must work for the people, not just their party.

Widely known for her debate skills on TV news shows and Diet sessions, Tsujimoto has been a key SDP member and her departure is expected to deal another blow to the already reeling party.