A perceptive story Wednesday in The Wall Street Journal helps explain why Congress has become an exceedingly partisan and angry place. The animosity the story describes, unfortunately, cannot be easily cured, especially under the current system used to elect members of Congress.

The Journal story links congressional crankiness with falling voter turnout. Hard-core conservatives and devout liberals always will vote, the theory goes, so when fewer people overall go to the polls, you can assume the voters not showing up are disproportionately part of the Great Middle, the people without specific agendas. When voting percentages drop, the extremes win.

This is reflected in Congress, where Republicans tend to be more conservative than the party as a whole and where Democrats tend to be more liberal. The House, then, increasingly represents not the breadth of American political beliefs, but the niches on the ends.

It is not clear whether the long-term voting patterns support this theory. For one thing, including 18- to 21-year-olds starting in the 1972 presidential election did more than apathy to drop the percentage of voters from around 60 percent to the mid 50s, where it was in 1992 when Bill Clinton won 20 years later. But the turnout in ’96 — a meager 49 percent — certainly suggests that lots of potential voters abstained recently and November’s mid-term election was had the lowest turnout since 1942.

That helps explain why members of Congress can disregard public opinion polls and know their seats are safe. They have a specific constituency to serve — those who vote and would at least consider voting for them; no one else counts. The result is the Judiciary Committee’s impeachment hearing writ large. The arguments during the last two weeks there left no room for compromise and no sense that there was any reason to deviate from the party line.

The antidote for this is to persuade more of the Great Middle to vote. But there is little in the commercially driven campaigns that dominate congressional races to inspire the poll-shy. If anything, the failure of campaign finance reform suggests the problem will be worse than ever in 2000. This suggests even greater partisanship to come because politicians will have less incentive to behave otherwise.

Curtis Gans, director of the Committee for the Study of the American Electorate, commented in the Journal that, “We will, if this trend continues, have an electorate occupied only by those with an interest in policy outcomes, and the ideologically zealous.”

America needs more fence-sitters.