Arima is not alone in his disillusionment. Recent opinion polls suggest that more than half of the Japanese electorate now share his view that neither party offers convincing solutions to problems that worry the public. While that’s bad news for everyone, it could prove particularly devastating for Abe, who is facing an important parliamentary election later this month. That’s because undecideds or swing voters are historically more likely to back for the opposition, whomever it is—if only to say no to the ruling party.

Abe’s decline has been precipitous. Within months of taking office last fall, his government was buffeted by mishap and scandal. A poor finish now in the Upper House vote could mark the beginning of the end for his struggling government; should the LDP lose a large number of seats, some observers expect Abe would be forced to step down.

Whatever happens, one thing is already clear: the P.M.’s fate will be decided not by party loyalists but by “floaters”—a growing legion of the undecided and the apathetic. Indeed, thanks to Abe’s lackluster administration, floaters now represent a majority of the electorate. The LDP’s membership has fallen from 3.3 million to 1 million in the last decade. And the consequences of this shift could be long lasting. Unaligned voters—who Ray Christensen, a political scientist at Brigham Young University, says “are the key to the election”—could switch to the opposition en masse. The result? “A big loss would not mean the fall of the LDP, but it would push Japan further toward a two-party system,” says Ikuo Kabashima, a political scientist at Tokyo University. And that would be a huge change for a place that’s been ruled by the LDP for most of the last 50 years.

It must be a bitter irony for Abe that he faces this predicament today. After all, his immediate forebear, the swashbuckling Koizumi, was a reformer who bolstered the LDP’s sagging popularity by promising sweeping change within the party and Japan at large. His camera-friendly “political theater” (as it was derided by his opponents) won over hosts of young disaffected voters. Koizumi also attracted large numbers of swing voters who might otherwise have backed the opposition. In retrospect, however, his accomplishments seem to have been temporary, a momentary halt in a steady slide toward popular disengagement. The real trouble began in the 1990s, when the LDP’s seeming inability to rejuvenate Japan’s economy—as well as its tolerance for corruption and confusing party realignment—caused the number of floaters to spike sharply, reaching nearly 50 percent (according to some political scientists). By going around party elders and appealing directly to the people, Koizumi reversed that trend. But now drift has set in once more, and the floaters are “going back to where they were before,” says Kabashima.

It wasn’t supposed to turn out this way; Abe was handpicked by his fellow LDP notables precisely in the hope that he could extend Koizumi’s populist legacy. But he has failed spectacularly on this count; indeed, some of Abe’s moves have seemed almost calculated to alienate voters. One of his first steps as prime minister, for example, was to readmit to the LDP a group of politicians who’d had been kicked out by Koizumi for opposing his reforms. Then Abe’s cabinet was rocked by a string of corruption allegations; one of his ministers even committed suicide in late May in the midst of a scandal. Most recently, the government was forced to confess that it had mislaid or confused more than 50 million pension records. Even though that mess wasn’t directly Abe’s fault or that of his cabinet, the prime minister has been hit by a wave of public outrage. (Pensions are a hot-button issue in this country where the population is rapidly aging.) And then there’s the general lack of direction. Yasushi Kudo, from the policy watchdog group Genron NPO, says Abe has failed to present a clear message to the public and has lost voters’ support by claiming Koizumi’s reformist mantle while pursuing an archconservative agenda.

To be fair, the public’s sense of disillusionment isn’t all Abe’s fault. The LDP’s support has been falling for years, particularly in the rural areas that were once its stronghold. Koizumi’s reforms, while popular in the cities, angered rural voters and weakened the LDP machine in these areas by reducing the public-works programs and subsidies on which the countryside depended.

But the fact remains that more votes are now up for grabs than ever before. Ichiro Ozawa, the leader of the Democratic Party, has started assiduously courting disgruntled rural districts—the “swing states” of this election. And the LDP is clearly worried, knowing how unpopular its chief has become (Abe’s popularity rating has dipped to 28 percent, according to some polls). An LDP leader was once caught observing aloud that he hoped floaters would “be taking a nap on Election Day”—betraying his belief that high voter turnout will only hurt the party. This view is now widely shared. According to one recent survey conducted jointly by the Asahi Shimbun newspaper and Tokyo University, a full quarter of voters who supported the LDP in 2005 say they would not vote for the party today.

If the DPJ can capitalize on this trend by making inroads into the countryside, it could well produce a major shakeup. Since their founding in 1998, the Democrats, who have pressed for liberal reforms, have generally enjoyed little popularity outside of their urban bastion. If they can change that now, the party could truly threaten the LDP’s half-century-old stranglehold on power.

Brigham Young’s Christensen cautions that a full revolution probably isn’t in the cards—not yet, at least. The LDP is still well entrenched and won’t be easily dislodged. Yet the mere fact that Japanese voters are finally growing less predictable promises to make life more interesting for the political establishment here in the years to come—and a lot less comfortable for Shinzo Abe and his allies.