To the casual observer, American and British politics appear to be on sharply divergent tracks. In the US, the party that represents the conservative interest, the Republicans, is in a state of historic collapse that makes the fall of the Roman Empire look like a narrow by-election defeat for the emperor in Parthia Northwest.

This week new woes were piled upon their miseries. It was revealed that awful conditions at the main military hospital for wounded soldiers returning from Iraq seem to have been tolerated with the sort of blasé disregard for others’ welfare that Donald Rumsfeld elevated into a governing philosophy.

Unlike Rummy in such circumstances, his successor Robert Gates ensured that heads rolled. But that has failed to shake the impression that once again the Bush Administration matches a lofty rhetoric about its global mission with a cruel insouciance for the poor souls who suffer its consequences.

Then Lewis “Scooter” Libby, Vice-President Dick Cheney’s Cardinal Richelieu, was convicted by a federal court of perjury and obstruction of justice. To pardon or not to pardon is the thorny question that confronts President Bush. Given the man’s near perfectly wrong performance on recent binary political choices, you’d be a fool to bet he’ll make the right one.

In Britain, meanwhile, it is the left-of-centre party that is in foggy disarray. Iraq, of course, is the common factor, the fons et origo of Labour’s and the Republicans’ weakness. But there are odd mirror images of the White House’s legal difficulties in the tightening web of inquiry that seems to be closing on No 10 over cash-for-honours. One day someone will explain to me why, after 800 years in which English monarchs and prime ministers have eagerly rolled out the ermine for those who keep them in the palaces to which they have become accustomed, it has suddenly become illegal to ennoble the odd rich friend or two. But no matter.

On the Tory side, the charms of David Cameron are rubbing off on a larger and larger slice of the electorate. A clever rebranding that has focused hard on the twin menace of chocolate oranges at supermarket checkouts and carbon dioxide emissions from other people’s combustion engines is paying dividends. Even nasty, outmoded, class-war-inspired innuendo about Mr Cameron’s past has naught availed. The Conservative leader seems to float gently above it all like the mesmeric curl of aromatic smoke from a glowing spliff.

So what we still call Left and Right are surely on different trajectories across the Atlantic. And yet inside the parties in both countries there are striking parallels. Both Democrats and Labour have serious leadership issues. Hillary Clinton and Gordon Brown both see themselves not just as the leading candidate but as the divinely ordained inheritor of the crown. Both have been the designated successors of their party for years, but both inspire dislike and despair among the party’s supporters who think — probably correctly — that the broader electorate is immune to their appeal. They are both quintessential top-down candidates, using similarly intimidatory tactics to lock up supporters and ward off potential rivals but failing to engender any warmth.

The closer their coronations come, the more treasonous their subjects feel. Growing numbers of Democrats and Labour people would love to be able to break free of the Hillary and Gordon trap. That is more likely to happen among the Democrats who have more time than does Labour. But in Britain there are those who fantasise that the studious David Miliband may be a sort of white North London version of Barack Obama.

On the Right too there are similarities in the US and the UK. In both Britain and America there is a gathering sense of despair among true conservatives about the condition of their party’s politics. True conservatives in Britain, who, rightly, see the country on the road to a state-controlled serfdom, hear Mr Cameron and wonder whether there is a genuinely conservative bone in his body. His instincts seem as busybodyishly paternalist as any new Labour bureaucrat.

In America, where conservative disillusionment is a more recent but no less palpable emotion, the three front-runners for the Republican presidential nomination are all, in a sense, Cameroonian in their frailty. With no obvious conservative candidate in the field, the contest between Rudolph Giuliani, John McCain and Mitt Romney is coming down for many conservatives to a choice of whom you hate least.

Currently, Mr Giuliani leads this Dutch auction. This has given rise to one of the more remarkable spectacles in politics — that of the libertine New Yorker Mr Giuliani feeling the love of Southern conservative Christians despite his record, views and predilections. Watching them embrace Mr Giuliani is like watching survivors from a shipwreck clinging to a giant turd in the water. It’s no one’s first choice of support from the briny waves but if you hold your nose it’s still better than any of the alternatives.

And yet conservatives, in their different ways, on both sides of the Atlantic, have no right to be picky. Iraq has discredited the very idea of an assertive foreign policy, globalisation’s malcontents are crying loudly for government help and years of ugly intolerance on the Right have turned off millions of decent voters.

In Britain Thatcherism is not in favour and in America Reaganism is not on offer. But that doesn’t mean reformist conservative candidates are inferior to their socialist and liberal opponents. In a hostile political environment a scaled-down conservatism is still better than no conservatism at all. The current generation of Republican and Conservative leaders recognise this and are working to renew conservatism rather than destroy it.

The right thing to do is not to make faces at this bandwagon but to jump aboard and keep trying to drive it in the right direction of freer markets, freer people. If they hang together in this struggle, conservatives have a good chance of advancing their cause as a governing strategy, not as an angry protest. It they do not, they will, most assuredly, hang separately.

Times Recommends

• Fantasy world fuelled by sex, drink and drugs
• In short, the story is growing on us again
• A literary feast that I can’t wolf down