The ruling Democratic Party of Japan (DPJ) started election of its leader Tuesday afternoon, the winner of which will become Japan's third prime minister in a year.

Prime Minister Naoto Kan and DPJ kingpin Ichiro Ozawa are vying for a majority of the 1,222 points up for grabs. DPJ Diet members, whose votes account for nearly 70 percent of the total points.

Kan was ahead of Ozawa, the former DPJ secretary-general, in terms of support from local lawmakers, party members, and was far more popular among general public.

Media reports said the focus is the votes of some 30 undecided DPJ lawmakers.

The voting began after the two contenders deliver their final 15-minute speeches at an extraordinary party convention starting at 2 p.m. at a Tokyo hotel on Tuesday.

Postal ballots of DPJ local assembly members, party members and rank-and-file supporters have already been sent to the party's headquarters and the results of their voting will also been disclosed at the convention.

Ozawa, often dubbed "the shadow shogun" of Japanese politics, is the main strategist for the DPJ to win a historic victory in the general election a year ago, breaking the Liberal Democratic Party's almost consecutive ruling for over half a century.

However, Ozawa resigned and is still embroiled in a political fund scandal. He is possibly to be indicted over the case.

Kan, who was finance minister before assuming office on June 8, was the first leader in many years not born into a blue-blooded political family. Kan's image is in contrast with that of Ozawa.