Shigeru Ishiba, the secretary general of Japan's ruling Liberal Democratic Party, is expected to turn down a cabinet position in a reshuffle scheduled for September 3, with the political grapevine suggesting that he is planning to challenge Prime Minister Shinzo Abe for the leadership.
Ishiba is reportedly unhappy that Abe wants him removed from his party post, effectively the No 2 in Japanese politics, and will turn down the offer of the new position of minister in charge of national security. Ishiba is in sharp disagreement with Abe on defence and security policies, and a cabinet position would compel him to toe the line.
Abe also appears to have lost some faith in his previously close ally, with questions raised about his management ability after the poor handling of local elections in Okinawa and Fukushima.
Ishiba has an interest in defence issues and has long favoured the creation of a basic law on security that would spell out unequivocally Japan's right to exercise collective self-defence. Abe has been more mindful of opposition to such a dramatic move and has stated his government will simply reinterpret the constitution to permit self-defence within limits.
"The prime minister and Mr Ishiba have fundamentally incompatible views on security legislation," a lawmaker close to Ishiba said. If Ishiba took up Abe's offer, it "could become a factor inhibiting the promotion of his own ideas" in the future, Kenji Kosaka said last week.
Jun Okumura, a visiting scholar at the Meiji Institute for Global Affairs, said there was "little doubt that if [Ishiba] had been asked to stay on as secretary general of the party, then he would not be contemplating a challenge to the prime minister". The party leadership traditionally carries with it the prime ministership.
The prime minister has been riding high in opinion polls since returning to the post in December 2012. The debate over collective self-defence and reinterpreting the constitution has cost him some goodwill, however, and his support rate fell below 50 per cent for the first time last month.
With that debate behind him - the legislation is expected to pass fairly smoothly early next year - the focus will once again turn to the economy, believes Okumura. "It all hinges on that and, my feeling would be that if the economy maintains its current trajectory of growth, then it will be difficult to challenge the prime minister," he said.
And while the economy is looking reasonably healthy, Abe must make a decision on whether to go ahead with the second phase of a hike in the consumption tax, to 10 per cent. The first increase triggered the biggest decline in spending since the March 2011 earthquake.
That, combined with any unforeseeable misfortunes that could befall the national and international economies, could embolden Ishiba.
"I would describe him as one of those rare individuals in politics who is really interested in policy, particularly in the areas of self-defence and agriculture," Okumura said. "You could even say that he verges on being obsessive."
Ishiba has a "large following" in the party, he added, as well as in the provinces. But in spite of his advocacy of an unequivocal right to collective self defence, Ishiba might prove a less divisive figure in the region than Abe, who has suffered frosty relations with both Beijing and Seoul.
"He would not go to the Yasukuni Shrine [honouring war dead, including war criminals] and he would not challenge the Kono Statement on the comfort women issue," he said, referring to a 1993 acknowledgement by Japan's then cabinet chief that the military recruited sex slaves to military-run brothels in the second world war. "And that would make him more palatable to China and South Korea."
"I would describe him as a functional hawk," he added.
Additional reporting by Kyodo