Indeed, after a strong campaign they could end 40 years of Democratic control in the House, history's longest period of one-party dominance there.

"I think the era of one-party dominance is over," Mr. Hennessey said.

Nonpartisan primaries sound like an attractive alternative to one-party dominance.

After 36 years of one-party dominance, Japan appears headed toward competitive politics.

During 65 years of one-party dominance, Mexico acquired a deservedly wretched reputation for electoral manipulation.

The ward system was subject to corruption and as with any one-party dominance, abuses arose.

In many ways, the political environment here mirrors the national one, with its brew of economic anxiety, corruption and voter weariness with one-party dominance.

So the Republican win may actually mean less one-party dominance.

But the rapid turnover also reflects something positive, a broad realignment of Japanese political life away from one-party dominance and toward democratic competition.

Not all one-party dominance is created equal.