Sometimes a political story morphs into an animal story. This seems to be happening to the Democrats in the US as they work out their future. Consider Howard Dean. A year ago Mr Dean withdrew from the presidential primaries yelping like a hound. Lately, feral Howard has reappeared as chairman of the Democratic National Committee. Now he spends his time savaging Republicans. There are Republican congressmen, he said recently, who "never made an honest living in their lives". As for the Republican party, it was "pretty much a white, Christian party". Howard the Hound goes for blood, and his party values him for his following among bloggers.

Calling Mr Dean a canine sounds harsh. But he is not the only dog in the Democratic party. There are the Blue Dogs.

This group of centrists in the House of Representatives chose their name to play off the old phrase "Yellow Dogs", referring to Southern party loyalists, of whom it was said: "they would vote for a yellow dog if it was a Democrat". The Blue Dogs, by contrast, seek to define themselves as independent. They feel "strangled blue" as their own party jerks leftward and Republicans pull to the right. They are mostly white, mostly Christian and mostly male (what about that, Howard?). But they do have their own brand of diversity: diversity in voting pattern. Blue Dogs sometimes vote with their party and sometimes vote with Republicans. This habit has not endeared them to their leadership. But the public often likes it. Since 1996, "Blue Pup" candidates have captured 18 Republican congressional seats.

Over lunch last week in New York, three Blue Dogs - the representatives Dennis Cardoza of California, Ed Case of Hawaii and Jim Cooper of Tennessee - made a data-stuffed argument that Republicans spend too much. With PowerPoint (appropriately blue) they pointed out the grim facts: the half-trillion dollar deficit; the national debt moving towards 20 times that by the end of the decade.

Part of the blame, the Blue Dogs charge, lies with a careless Republican-led Congress. Members sometimes fail even to read the legislation they approve. This summer Congress is working on two obscenely expensive projects, a transportation and an energy bill. Nearly every Republican on Capitol Hill must acknowledge wasteful expenditure. One egregious example has been Republican Finance Committee chairman Charles Grassley's rainforest park - in Iowa. Critics call it "Grassley's Rainforest Pork". (I told you this was an animal story.) If congressional Democrats are dogs, Republican congressmen are porkers.

Blue Dogs allege that President George W. Bush too is also at fault. He is failing to block the path to the trough. Former presidents Bill Clinton and George H.W. Bush vetoed legislation they did not like. This Mr Bush has not. Nor does he kill wasteful projects the way Mr Clinton did. Because Republicans also control both legislative chambers, no countervailing force slows their spending. The war on terror makes political opposition feel unpatriotic. Like wartime presidents before him Mr Bush uses war to justify spending that would otherwise be challenged. But war cannot explain his biggest sin: permitting the creation of an $8,000bn government entitlement - prescription drugs for seniors.

The Blue Dogs warn of danger ahead. Future obligations will convert deficits into debt. The federal debt will double this decade. Congress, they say, must restrain spending, punish agencies that flunk their audits, cut back Medicare and order collection of uncollected taxes. If Washington does not act, we can all put our paws over our eyes and pray.

There are flaws in the Blue Dog position. The first is the reality that, given control of both houses and the executive, the Democrats would outspend even the piggiest Republican Congress. The second is that the White House is not as greedy as the Blue Dogs suggest. Mr Bush has fought to kill, reduce or reform more than 150 government programmes. The White House has asked Congress to cut non-defence, non-homeland security spending in the 2006 budget.

Another problem is the Blue Dog preoccupation with deficits rather than growth. They note that the US averages stronger growth than does Europe. Yet the Dogs fail to acknowledge that the relatively low tax rates in the US have contributed to that growth.

Finally there is Social Security. Reforming the national pension plan is the single most obvious thing that can help to improve US financial standing. Bipartisan support is crucial. Yet the Blue Dogs are conspicuously absent from the president's reform campaign.

Still, next to the other Democratic type - Mr Dean - the Blue Dogs have appeal. The White House can learn from them. Also important, however, is that the Democratic party focus on these studious centrists. The Blue Dogs can rescue their party and it would be unwise to discount them. Every dog has his day.

* Last week I misquoted Paul Rosenstein-Rodan in regard to development economics. What he said was: "When the World Bank thinks it is financing an electric power station, it is really financing a brothel."

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