The longer Barack Obama is in the White House, the more closely he comes to resemble Tony Blair. Blair’s greatest strength was his ability to masquerade as a man without ideology, a pragmatist interested simply in doing what works who stigmatises his opponents as irrational extremists.

In reality, everyone has an ideology. Pragmatism is ideological. You can’t judge what works without knowing what goals you want to achieve, and goals are defined by values. But like Blair, Obama is a master of false reasonableness, a political genius with a tremendous rhetorical ability to reframe issues and put himself at the centre of them.

Obama’s latest State of the Union address was a brilliant case in point. The institution of the State of the Union is deeply tired. Each address flows indistinguishably into the next, and most of them amount to nothing. This one was no better than most, and duller than some. But it highlighted Obama’s gift for making his points in a way that wrong-foots his opponents.

He harshly condemned the sequester, which will automatically slice federal spending later this year. That’s not surprising: preventing the sequester would allow Obama another shot at raising taxes. What he neglected to mention was that the sequester was his idea. Even now, the White House’s fact sheet describes the sequester as “a win for the economy and budget discipline”.

He praised “investment” in early education, but the Department of Health and Human Services has found that its $8bn Head Start programme “had little to no impact on cognitive, social-emotional, health, or parenting practices of participants”. He demanded action on climate change by referring to “Superstorm Sandy,” which not only confuses the weather with the climate, but ignored the fact that Sandy was not even a Category 1 hurricane when it made landfall.

What is curious is how this approach both works and fails to work. It worked well enough to win him the election, and to the extent that instant polling is reliable, it appears to have played well on the night of the State of the Union address. But when Gallup recently surveyed the American public, they found something surprising and different. The only area when Obama commands majority support is on national defence, where he benefits from Afghanistan fatigue and from the perception that he is even more willing to use drones than George W Bush. But on immigration, energy, gun policy, taxes, the economy, the Middle East, and the budget deficit, he is under water, often substantially.

This is reminiscent of the political situation in Britain in the early 2000s, when people supported Conservative positions until they were told they were Conservative. It was not the policies that were toxic: it was the fact that they were supported by the Conservative Party.

Much the same is true in the US today: Obama has not succeeded in detoxifying his positions, but he has successfully made the Republican Party toxic.

It was a sign of the success of this strategy that the only time Obama looked vulnerable in the last election was after the first debate. Mitt Romney momentarily broke through the Obama-fuelled smoke screen by demonstrating that he was actually intelligent, articulate, and reasonable. But relying on these sorts of moments to appear with regularity is a losing strategy.

The danger for American conservatives is that they will go down the road pioneered by David Cameron, who managed to fumble away a winnable election by focusing so relentlessly on detoxifying the Conservative brand and picking modernising candidates that he was unable to capitalise when Gordon Brown and the British economy stumbled.

The problem with this approach is that, at root, it accepts the fallacy of pragmatism. By trying to co-opt the electoral virtues of false reasonableness, it ends up having no positive programme. The Cameron campaign was not just a disappointment in 2010: it has, with honourable exceptions in the realms of welfare and education, disappointed since then. It is hard to see why anyone in Britain who did not vote Tory in 2010 would vote Conservative in 2015. In other words, if you want to be a pragmatist in politics, you also have to be cynical enough to discard pragmatism when it comes time to deciding what you actually want to do. Conservatives who identify with Blair’s pragmatism too often end up mistaking shadow for substance. Worse, since the natural instinct of the do-what-works politician is to pander to interest groups, pragmatism further plays into the hands of liberalism by atomising society into groups of antagonistic benefit-seekers.

Not for nothing does every State of ?the Union address now feature a laundry list of goodies that will supposedly benefit constituency after constituency.

It is natural for conservatives to argue that, in the face of Obama’s second-term progressive focus on immigration, gun control, tax hikes, defence draw-downs, and investments – a code word for more spending – they need to come together. Natural, but wrong.

One of the great strengths of ?American conservatism over the past 50 years has been its ability to argue with itself, and to reinvent itself. Libertarianism is showing new strength in the US today, especially among younger voters, and though I am no libertarian, I welcome the argument.

As long as it is a respectful debate about substance, it will make us stronger, not weaker. In Britain, Conservatives went down a different path: they decided to stop arguing and go along with Cameron.

That proved to be a mistake.The free market works as well with ideas as it does with money. The conservative agenda in the US now begins with keeping that free market faith.