British politics just now resembles the mirror scene in “Duck Soup,” one of the funniest pieces of pantomime the Marx brothers ever made. Groucho, dressed in nightshirt, suddenly encounters Harpo, who – complete with trademark moustache, spectacles and cigar – is pretending to be his mirror-image. Groucho tries to catch out his double, and the two even swap headgear, but each time Harpo is ahead of him.

This is the game being played by Conservative leader David Cameron. Everything Tony Blair does, he can do better. Just as Mr. Blair stole Margaret Thatcher’s economic policies in the mid-1990s, so Mr. Cameron is now stealing Mr. Blair’s. Just as Mr. Blair had to stage a showdown with the Leftist dinosaurs in the Labor Party, so Mr. Cameron is staging his own showdown with the Rightist dinosaurs in the Tory Party.

Whether Mr. Blair tacks to Left or Right, Mr. Cameron tries to anticipate his every move. And he does it with an air of self-righteousness that recalls the attitude attributed by the Prophet Isaiah to the Israelites: “Stand by thyself, come not near to me; for I am holier than thou.” Worried about global warming? Tories are greener than thou. Worried about poverty? Tories are more compassionate than thou. You name it – Tories will imitate it.

Absurd? Of course it is – and everybody involved knows it. Mr. Cameron knows that he is not really Mr. Blair’s doppelganger and vice versa; so does the audience, i.e., the British public. But the electorate seems to be enjoying the spectacle too much to worry about its implications for good government. Polls have shown Labor and the Conservatives neck-and-neck ever since Mr. Cameron took over last December.

In a country that has been used to two ideologically opposed political camps for at least a century, this convergence of the two main parties is a novel experience. Americans are used to Republicans and Democrats straddling the conservative-liberal divide, but the British are still getting used to the idea of a Labor prime minister whose closest ally is George W. Bush. Now they have the prospect of a Conservative leader who is so determined to shed his party’s negative image that he is throwing out not only the baby with the bathwater, but the bath too.

Just how far Mr. Cameron is prepared to go has been illustrated this week. He has published “Built to Last,” a “statement of aims and values” to which all 250,000 members of the Conservative party will be invited to sign up in a ballot.

It remains to be seen whether this will serve any useful purpose other than as a loyalty test. Apart from the fact that Conservatives have traditionally left ideology to the Left – there is no Tory “Communist Manifesto,” and for very good reasons – the woolly liberalism of this document is not calculated to stir the feelings of the party faithful: “We believe in the role of government as a force for good.” “It is our moral obligation to make poverty history.”

Equally worrying for Conservatives is Mr. Cameron’s attempt to have one’s cake and eat it: “We will ensure strong defense and the effective enforcement of laws that balance liberty and safety – instead of ineffective authoritarianism which puts both freedom and security at risk.” In other words: We Tories may have dithered over the Iraq war, exploited anti-Americanism and voted against anti-terrorism laws – but you can still trust us with the defense of the realm.

The government, he declares, “should support families and marriage.” But, rather than reverse the present fiscal bias in order to encourage couples to marry and put children first, Mr. Cameron takes refuge in obfuscation and equivocation: “We will support the choices that women make about their work and home lives, not impose choices on them.”

It is the same on the economy: “We will put economic stability and fiscal responsibility first. They must come before tax cuts.” As if Europe’s stagnation were the result of low taxes! Where, I wonder, would Mr. Cameron place Laffer’s Curve? Supply-side economics – or “Sex and the City”?

For Mr. Cameron “the quality of life matters, as well as the quantity of money.” A man who can afford a million-dollar “green” makeover for his house can also af ford to “enhance our environment by seeking a long-term cross-party consensus on sustainable development and climate change – instead of short-term thinking and surrender to vested interests.”

Well, over the last decade environmentalism has itself grown into the biggest vested interest of all – to the point where claims that are in principle unfalsifiable are treated as scientific certainties. Mr. Cameron mercifully does not repeat his earlier criticisms of “big business,” but “short-term thinking” is not a bad phrase to describe a Conservative politician who tries to capitalize on anti-capitalism.

While it is Mr. Cameron’s job to shadow Mr. Blair – his team is by tradition known as the “Shadow Cabinet” – he doesn’t have to take the term quite so literally. The Cameron strategy is about to be tested. This week Mr. Blair published his long-awaited Education Bill. Mr. Cameron has promised to get on board this flagship, mainly to embarrass Mr. Blair, while the Labor Left want to sink it. To appease the Labor rebels, the Bill has been emasculated. It doesn’t even mention what was supposed to be its main innovation: “trust schools”, which are supposed to enjoy more independence from local government.

Mr. Blair, however, has signaled that he will push the Bill through, even if he has to rely on Tory votes to do it. He knows that he risks detaching himself from his party, rather as Ariel Sharon detached himself from Likud by cutting the settlers loose. Unlike his septuagenarian Israeli counterpart, struck down while still in harness, Mr. Blair has already announced his impending departure, so he is unlikely to found a new party.

More’s the pity. For if Mr. Blair were released from the dead hand of the Labor Party, he might be able to tackle the most profound problem facing Britain: Islamism. A poll last weekend showed that 40% of British Muslims demand sharia law. Mr. Blair firmly rejects that demand. Mr. Cameron has so far had nothing to say on Islam. It is good that his Tory manifesto is inspired more by Groucho than by Karl Marx. But Mr. Cameron will not be elected as long as he ducks the issue that keeps people awake at night: the Islamicization of Britain.