Democratic Party of Japan lawmaker Yuzuru Tsuzuki submitted his resignation to the House of Representatives on Tuesday, shortly after the Supreme Court upheld suspended sentences handed to his aides for paying election campaign workers in violation of the election law.

With the Supreme Court decision, Tsuzuki would probably have been stripped of his Diet seat due to a provision in the Public Offices Election Law that holds candidates guilty by association for election law violations committed by senior aides, including a campaign manager, finance officer or secretary.

"It's not that Tsuzuki is being incriminated at this point," DPJ leader Katsuya Okada later told a news conference. "But it is my understanding that he felt a responsibility to step down because there was a possibility he could be called into account" under the legal provision.

"We'd like to offer voters our heartfelt apologies over the incident, which has led to the parties involved being convicted this way," Okada added.

In last November's general election, Tsuzuki ran unsuccessfully in Aichi Prefecture's No. 15 single-seat district. He ended up with a Diet seat under the proportional representation segment of the election.

Tsuzuki's chief election campaign officer, Toshihiko Kusano, and his secretary, Nobumoto Iseki, were convicted at the lower court level of violating the Public Offices Election Law, which stipulates that campaign workers must be registered before being paid. They had promised 800 yen per hour to housewives and other unregistered volunteers recruited to engage in phone canvassing.