The prime minister said he will take "decisive action" if it proves necessary.
Recent opinion polls indicate that Kan is ahead of Ozawa by about four-to-one in the DPJ presidential race, although Ozawa commands the direct support of 150 lawmakers and a further 60 from former Prime Minister Yukio Hatoyama's intraparty group.
Hatoyama, having first pledged to support Kan, reversed his decision in favor of Ozawa, but Kan has so far been backed by about 70 DPJ lawmakers belonging to a group headed either by transport minister Seiji Maehara or Finance Minister Yoshihiko Noda, in addition to his own intraparty group of about 50 lawmakers.
Kan has also garnered far more public support than his adversary, according to the results of recent polls published in a number of notable Japanese dailies.
In this presidential election, rank-and-file party supporters will be eligible to vote, in addition to 412 DPJ lawmakers, as well as local assembly members.
The 340,000 strong rank-and-file party members or supporters will undoubtedly sway the outcome of the vote on Sept. 14, the outcome of which many political pundits are saying is too close to call at the moment.
The winner of the party's presidential election will almost certainly become Japan's prime minister because the DPJ holds a majority in the more powerful lower house of parliament.
Should Ozawa defeat Kan for the party's top post, he will become the third prime minister since the DPJ swept to power in an historic defeat of the Liberal Democratic Party (LDP) last September, bringing an end to almost half a century of unbroken LDP rule.
Ozawa has largely been credited as the brains behind the DPJ's election success that ousted the Liberals.
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Photos: Japanese PM, former DPJ leader hold joint press conference>>
Japan's ruling party leadership race officially starts
TOKYO, Sept. 1 (Xinhua) -- The race for the leadership of the ruling Democratic Party of Japan (DPJ) officially started Wednesday with Prime Minister Naoto Kan going head-to-head with the party's former No. 2 Ichiro Ozawa, in a contest that will ultimately decide who will be Japan's next prime minister.
Both Kan and Ozawa, following talks held on Tuesday, filed their official candidacies Wednesday morning for the Sept. 14 election, at the party's headquarters and thereafter unveiled their policy platforms and went on to hold a joint news conference in the afternoon. Full story
Kan to face Ozawa in ruling DPJ presidential election
TOKYO, Aug. 31 (Xinhua) -- Japanese Prime Minister Naoto Kan on Tuesday evening held talks with former Democratic Party of Japan ( DPJ) Secretary-General Ichiro Ozawa, aiming at discussing ways the two political heavyweights can cooperate in governing the country despite going head-to-head in the Sept. 14 DPJ leadership election.
Having failed to convince Ozawa to give up the leadership battle, with the party's former No. 2 reiterating his intention to run against Kan, despite the possible split it could cause within the ruling party, the two met for their first face-to-face meeting since the DPJ failed to consolidate their power in the Upper House election on July 14. Full story
