A House of Representatives committee began deliberations Monday on a controversial electoral reform bill that was the center of an 18-day opposition Diet boycott.

The Lower House committee on political ethics and the Public Office Election Law began the deliberations in the afternoon, with both ruling and opposition members present.

The ruling coalition -- the Liberal Democratic Party, New Komeito and the New Conservative Party -- plans to enact the bill, which would revise the House of Councilors electoral system, as early as today in a vote at a Lower House plenary session.

But the opposition bloc -- the Democratic Party of Japan, the Japanese Communist Party, the Social Democratic Party and the Liberal Party -- plans to seek thorough deliberations.

In addition, the DPJ plans to submit its own electoral reform plan, DPJ officials said.

The opposition bloc abandoned its boycott on Friday, a day after the ruling coalition railroaded the bill through the Upper House.

The bill would revise the proportional representation segment of the Upper House's electoral system so that ballots can be cast either for individual candidates on party lists or for the parties themselves. The current system allows votes only for parties.

The new system would allocate votes for a particular candidate to benefit other candidates on a party's proportional representation list.

The bill would also cut 10 of the 252 Upper House seats.

The opposition parties charge that the ruling bloc is seeking the changes merely to boost its chances in the next Upper House election -- by fielding big-name candidates, for example -- and that the changes would make election campaigns more costly.