Three weeks after its debut, the administration of Prime Minister Junichiro Koizumi continues to command high popularity. In opinion polls immediately after its inauguration April 26, the new administration received record approval ratings of over 80 percent. The "Koizumi boom" is likely to last for some time.

A variety of reasons can be given for this. The first is Koizumi's unique personality. He has long been called a "maverick" in political circles. While a member of the defunct Fukuda faction (headed by former Prime Minister Takeo Fukuda), he was something of a loner. He does not follow the crowd. He is not a theoretical type but rather a man of sensibility. He hates "harageri," a way of subtle communication that relies chiefly on psychological interaction. He expresses himself in plain language.

In many ways Koizumi is very different from his predecessor, former Prime Minister Yoshiro Mori. In the Liberal Democratic Party's presidential election last month, Koizumi advocated a breakup of the intraparty factions and defeated former Prime Minister Ryutaro Hashimoto, head of the largest faction. It was a dramatic victory that demonstrated his personal popularity not only with LDP members disillusioned with pork-barrel politics but also with the public.

Koizumi himself was so surprised at his high ratings that he was quoted as saying, half-jokingly: "It looks like I'm reaching the apex of my popularity. I have nowhere to go but down." According to sources close to him, the prime minister also told them, with a wry smile: "The three days after taking office was the time of my life. I wonder just how long I can last. If I last three months, maybe I can stay in office for three years. Who knows?"

The last remark is highly significant. In less than three months -- on July 29, to be exact -- an Upper House election will be held. If Koizumi's popularity ratings then stay at least around 50 percent, the LDP almost certainly will win. If that happens, Koizumi certainly will be re-elected LDP president.

As a result, the Koizumi administration will be long-lived, perhaps lasting two or three years. So it is critically important how his popularity develops over the next three months or so. Whether his administration sinks or swims depends on his ratings in this period.

His popularity hinges on two questions. One is whether his reform campaign will make good progress. The other is how his critics in his own party, now largely silent, will move in the next few months.

Moves by the opposition parties, particularly the Democratic Party of Japan, will not be much of a factor because they are more or less sympathetic to the new administration. By contrast, many Liberal Democrats are cool or aloof to, or critical of, the new Cabinet.

In particular, the Hashimoto faction, which lost the presidential election, and the second largest faction, the Eto-Kamei group, hold a deep grudge against Koizumi. With an Upper House poll coming up, an open revolt is unlikely. But if the going in the Diet gets rough as a result of administration mistakes, this smoldering anti-Koizumi feeling could come into the open.

The opposition, meanwhile, faces a dilemma in dealing with Koizumi's reform drive. This is particularly true of the DPJ, the largest opposition party. If it gets too close to his policies, the differences between the LDP and DPJ will become fuzzy. As a result, the DPJ will face an uphill battle in the coming election.

Moreover, the DPJ will alienate other opposition parties if it leans too closely toward to the Koizumi lines. Mutual mistrust between them will discourage joint election campaigning. What's more, the DPJ leadership could come under attack from younger members friendly to the Koizumi lineup in the LDP.

Thus, the birth of the Koizumi administration threatens to affect the two largest parties, the LDP and DPJ, in subtle ways. If things develop in this way, they could touch off a round of political realignments before or after the July election. Another possibility is that the current tripartite ruling coalition of the LDP, New Komeito and the New Conservative Party might collapse, depending on the election outcome.