FRANK RICH, of the New York Times, accuses the Bush administration of conducting a “quiet coup, ultimately more insidious than a blatant putsch like General Musharraf's”. Ann Coulter, of here, there and everywhere, says the Democratic Party is so dumb that “it's as if all the brain-damaged people in America got together and formed a voting block”. And every day thousands of would-be Riches and Coulters inject similar sentiments into the blogosphere.

This sort of partisan rhetoric is tedious. But hasn't American politics always been full of it? In the 1828 election Andrew Jackson's supporters accused John Quincy Adams of being a drunken fornicator who sold virgins into white slavery, while Adams's supporters accused Jackson of committing 18 murders. And isn't partisanship exactly what strong democracy is about?

The argument over the merits of partisanship has itself led to furious divisions. Partisans welcome it, while moderates deplore it. But the past few years have produced a body of scholarly literature that raises the discussion to a more elevated level. And now Ronald Brownstein, one of America's best political journalists, has produced a sparkling new book on the subject, “The Second Civil War: How Extreme Partisanship Has Paralysed Washington and Polarised America”.

This pile of literature points to two conclusions. The first is that partisanship has produced plenty of benefits. It offers voters “a choice, not an echo”, and stimulates interest in politics. The 2004 election produced a turnout of 61%—huge by American standards, and more than six percentage points higher than in the 2000 election. But the second conclusion is that partisanship has gone too far. America is more divided than it has been for 40 years, and concomitant divisiveness is hampering its ability to deal with pressing problems both at home and abroad.

Richard Hofstadter, one of America's greatest political historians, once observed that each party was a hotch-potch of conflicting interests, and that the parties' main business was to seek compromise. That is no longer the case. George Bush has happily governed as “president of half the country” (the partisan gap in his approval rating has reached an astonishing 70%). Congress has started to act like a parliament. Voting along partisan lines in Mr Bush's first term ran at 90% among House Republicans and 89% among Senate Republicans (the figures for Democrats were 86% and 85% respectively). And Americans have taken to living in political ghettoes. In 1976, when Jimmy Carter beat Gerald Ford by two percentage points, only 27% of Americans lived in “landslide counties”, where one candidate won by 20 points or more. In 2004, when Mr Bush beat John Kerry by a similar margin, 48% of Americans lived in such places.

This partisan revolution is largely the result of what Mr Brownstein calls “the great sorting out”. White southerners have changed their party affiliation from Democratic to Republican. And ideologues of the left and right have divided themselves along party lines. But the “sorting out” has been reinforced by political tinkering. Gerrymandering means that a growing number of politicians represent super-majorities. And the primary-election system means that they have every incentive to appeal to the most partisan people in their districts.

In his farewell address in 1796, George Washington took aim at the dangers of “faction”—arguing that it distracts attention from important questions, weakens the government and “agitates the community with ill-founded jealousies and false alarms”. But if anything this understates the dangers of today's hyper-polarisation. Partisanship has embittered the 49% of the electorate who voted against Mr Bush. It has alienated the 45% of voters who described themselves as “moderate”. It has weakened the checks and balances built into Congress (the Senate, supposedly the more deliberative chamber, has not yet even got around to debating Mr Bush's “surge” in Iraq). And it has made it impossible to deal with long-term problems, such as the budget deficit and Social Security reform, which require mutual sacrifices and complex deal-making.

This is particularly dangerous when it comes to foreign policy. The explosive divisions over the Iraq war have weakened Mr Bush, who might have corrected his strategy earlier if he had faced serious scrutiny from Congress. And they have certainly weakened America abroad. They not only signal to America's enemies that the country is divided, but also suggest that policy might change dramatically with a new president. Hyper-power and hyper-partisanship make bad bedfellows.

Sinking fires

Is there any chance that the trend can be reversed? Scholars such as Bill Galston of the Brookings Institution have suggested various institutional reforms, from the far-fetched (reintroducing multi-member districts) to the sensible (taking redistricting out of the hands of party hacks). But there are signs, as Mr Brownstein argues, that the system is beginning to fix itself.

In his second term Mr Bush learned that partisanship is a dangerous weapon—powerful when things are going well, but self-destructive when things turn against you. His bid to reform Social Security turned into a flop because the Democrats believed they had nothing to gain from co-operation.

For their part the resurgent Democrats are likely to be less partisan than the Republicans. The Democratic coalition is much less homogeneous than the Republican one. Only 52% of Democratic voters describe themselves as liberals, compared with the 77% of Republican voters who call themselves conservatives. The partisan fires stoked high for the past 40 years are not going to gutter out; the two leading candidates on both sides, Rudy Giuliani and Hillary Clinton, are notably polarising figures. But they may burn less fiercely than they did under Mr Bush.