If the weekend polls are a foreshadow of the eventual outcome, the LDP is likely to be limited to around 30% of the aggregate popular vote in the proportional districts—and still win a simple majority in the December 17 House of Representatives (HoR). Even if it falls short of a majority, the 30 or so seats that Komeito will win should be more than enough to secure Shinzo Abe the prime minister’s office with the first HoR ballot. This means that the LDP-Komeito coalition does not need a third wheel that would create governance issues. However, it will have enough trouble getting legislation done in any case since it should fall well short of the 320 seats needed for a supermajority to override a House of Councillors veto. And with a low percentage of the popular vote, claims of a popular mandate will not generate much sympathy in the media. What follows is an explanation of the cursory look at the figures and the reasoning behind my conclusion.
In the five HoR general elections (1996, 2000, 2003, 2005, 2009) under the mixed, single member district (SMD)-regional proportional district (RPD) electoral system, the LDP has taken as many as 48.5% (233) of the 480 seats while winning only 28.81% of the RPD votes (2000). This was possible because the LDP’s SMD candidates receive an aggregate 10 percentage-point bump or so from the well-disciplined Sokagakkai supporters of Komeito. In the upcoming election, this would give an LPD SMD candidate 40% or so of the vote. That is a pretty high threshold for a DPJ candidate, who under the same assumptions has an average of 25% of the votes. Or a JRP candidate with 15%. The LDP dropped to 25% (119) of the seats with 26.73% of the RPD votes in 2009. But that was because the DPJ was strong enough to sweep 42.21% and 47.43% of the SMD and RPD votes respectively. The JRP is likely to do well enough in its Kansai stronghold to easily emerge as the top party there, and JRP-Your Party coordination will produce some synergy between their SMD candidates’ lists, at a minimum reducing the number of conflicting candidates. However, neither of these parties has the kind of control over their RPD supporters that, say, Komeito or the Communist Party has or a large roster of candidates to take full advantage of its underlying support. Moreover, the JRP is a recent concoction hastily cobbled together in anticipation of the election out of mainly DPJ refugees and long-in-the-tooth LDP exiles bringing together different policy agendas and political styles, making coordination with a third party all the more tricky. Given this backdrop, only a significant lead by the DPJ over the LDP in the underlying support would knock the LDP from pole position when the Diet reconvenes immediate after the election to select a new prime minister. There is a disproportionately large segment of the unaligned voters that has yet to show an RPD preference for any of the 12 parties. But that is more likely to break for one of the Third Force movements, not the DPJ, and the JRP (or Your Party or the Ozawa-Tada alliance for that matter) does not have the kind of national SMD coverage that would enable it to fully cash in on that increasingly unlikely bounty.