Democratic Party of Japan Secretary General Ichiro Ozawa urged party colleagues Friday to intensify their efforts to score a resounding victory in this summer's upper house election.

Ozawa told an annual New Year gathering of lawmakers held at his home in Tokyo that winning the majority of House of Councillors seats is crucial for the ruling party, which currently needs help from small coalition partners to ensure smooth passage of legislation.

"It's very important to go through crucial policymaking processes and get (legislation) passed in parliament with our own power," Ozawa said.

The upper house election will be the first national poll since the launch of the DPJ-led coalition government in September 2009 following the party's landslide victory in the general election for the powerful lower house in late August.

Half of the 242 upper house seats come up for election every three years — 73 in constituencies and 48 in the proportional representation segment. The DPJ plans to field multiple candidates in many of the 12 constituencies from which two lawmakers will be elected.

"It's going to be very tough for us because our candidates will compete against each other there," Ozawa said. "But we will not be able to secure a majority unless we overcome this hardship as long as the current election system is in place."

Ozawa reiterated that a DPJ victory in the upper house poll would not necessarily mean the party will abandon its coalition partnership with the Social Democratic Party and the People's New Party.

Friday's meeting was attended by more than 150 lawmakers, including Deputy Prime Minister Naoto Kan and Chief Cabinet Secretary Hirofumi Hirano.