Former education minister Makiko Tanaka of the Democratic Party of Japan lost her seat in Niigata Prefecture in Sunday’s general election.

Tanaka’s defeat to Liberal Democratic Party contender Tadayoshi Nagashima in the No. 5 district was mostly due to her weakening support from local, aging voters, observers said.

Nagashima, former mayor of the village of Yamakoshi, which was heavily damaged by the 2004 quake in Niigata, managed to garner wider support from rural parts of the prefecture by taking advantage of his leadership in reviving the communities hit.

The daughter of the late Prime Minister Kakuei Tanaka, who wielded immense power during Japan’s intense economic spurt in the 1970s, Tanaka won her Niigata No. 5 seat six consecutive times starting in 1993.

Her defeat means the end of what political observers call the “Tanaka Empire,” which ran Niigata for decades.

During her campaign, Tanaka told voters: “If I lose this time, that will be the end. I won’t change my electoral district or change my party affiliation to run again.”

As education minister, the outspoken lawmaker stirred controversy — something she often did when she was foreign minister under Junichiro Koizumi’s LDP.

In November, Tanaka said she intended to block plans to open three new universities in fiscal 2013, despite their approval, but later backpedaled after drawing heavy fire from concerned parties.