THREE years ago Zell Miller, then a Democratic senator for Georgia, published an anguished book entitled “A National Party No More: The Conscience of a Conservative Democrat”. Today, though, the people who are in that very danger are the Republicans rather than the Democrats.

The Republicans are now engaged in a fierce debate about the meaning of last month's mid-term defeat. Was there anything more to their loss of both chambers of Congress than the six-year itch and an unpopular war? Do they need to press ahead with the conservative agenda or should they revise it? The debate is lively. But it is missing an important aspect: the Zell Miller dimension. Is the Republican Party in danger of shrinking to its southern base? And is it shrinking at exactly the same time that the Democrats are becoming a more national party?

The extent of the southernisation of the Republican Party is astonishing. The party was all but wiped out in its historic base, the north-east. There is now only one Republican in the 22-strong New England House delegation. New Hampshire kicked out its two Republican congressmen (and gave Democrats a majority in both state houses for the first time since 1874). Massachusetts ended 16 years of Republican occupation of the governor's mansion. Rhode Island decapitated Lincoln Chafee despite his moderate record. New York installed Democrats in every statewide office for the first time since 1938.

The Republicans also suffered big losses in a region that voted solidly for Bush in 2004—the Mountain West. Three Republicans lost house seats. Conrad Burns lost his Senate seat in Montana (59% for Bush in 2004). Democrats now control five of the eight governorships in the region, compared with none in 2000.

The only place where the national tide had little impact was in the South. The Democrats made a few inroads in the periphery—winning a Senate seat in Virginia and House seats in North Carolina, Florida and Texas. But deep southern states such as Georgia and Mississippi remained unchanged. Exit polls showed that only 36% of white voters in the South voted for Democratic House candidates; it was 58% in the north-east.

The problem for the Republicans is that a regional stronghold can become a prison. The South has one of the most distinctive cultures in the United States—far more jingoistic than the rest of the country and far more religious. Fifty-eight per cent of deep southerners identify themselves as either evangelical or born-again compared with a third of non-southerners (the figure in Mississippi is 73%). But for every non-southerner who waxes lyrical about southern charm there are many more who associate the South with racial bigotry and cultural backwardness. The 2006 election—which saw social conservatives such as Rick Santorum and Kenneth Blackwell go down to humiliating defeat—suggests that non-southerners have grown particularly impatient with the South's brand of in-your-face religiosity.

For once Bill Frist, an outgoing Republican senator from Tennessee, has read the runes correctly in announcing this week that he will not run for president. Mr Frist is too deeply associated with pandering to the religious right—particularly over the Terri Schiavo affair—to have a chance of winning nationally. But Mitt Romney, the outgoing governor of Massachusetts, could well be in the process of falling into the trap. Mr Romney thinks the only way that he can persuade the evangelicals who control the southern party to forgive him his Mormonism is to turn himself into a red-blooded social conservative. But the more he does that, the more he alienates people outside the South.

The Republican Party's problems are made worse by the fact that the Democrats have done a good deal to escape from their own Democratic prison. Beyond their gains in the Mountain West, they will be able to display some interesting new faces when the next Congress assembles in January: like Brad Ellsworth of Indiana, who boasts an A-grade from the National Rifle Association, Mike Weaver of Kentucky, who opposes abortion rights, Heath Shuler, of North Carolina, who boasts that he is “pro-business, pro-life and pro-gun”, and Jim Webb of Virginia, who likes nothing better than denouncing the liberal elite.

Still time to rethink

One should be wary of reading too much into the result of a single election—particularly one conducted during the sixth year of a presidency and during a disastrous war. The Democratic leadership is still dominated by bicoastal liberals. The two leading Republican presidential candidates, John McCain and Rudy Giuliani, are from Arizona and New York. Arnold Schwarzenegger won a resounding re-election by taking to the middle. But the Democratic advances were more than just a fluke. Howard Dean, the party chairman, made a point of running a 50-state strategy in 2006. But even before that, the party had worked hard to recruit candidates who looked more like America and less like Harvard Yard: Brian Schweitzer, who was elected governor of Montana in 2004, says that “we don't scare 'em. We are the kind of people who go to church on Sunday, drive a pickup and lower taxes when we can.”

The danger for the Republicans is that they will respond to these Democratic advances by retreating to their heartland. The incoming Republican delegation will be more southern and more conservative than ever. It is hardly encouraging that the Senate Republicans have just reinstalled Mississippi's Trent Lott as one of their leaders—a man who had to give up the top job in 2002 for making a racist remark. There are plenty of Republican activists who think that the future lies in becoming ever more conservative, and not worrying too much about the slow-growing north-east. That sort of thinking led the Democrats to become the Party of Taxachusetts and Michael Dukakis. The Republicans need a Zell Miller of their own.