THE Obama campaign is up to something interesting. After months of attack ads portraying Mitt Romney as a heartless rich man who became rich by doing heartless things, and endless stump speeches, campaign briefings and rapid rebuttal emails more or less accusing the Republican of lying, a new approach is becoming dominant. The new tack is to stress, firmly and repeatedly, that Mr Romney is a serial concealer of truths and hider of inconvenient facts. I think this could be a useful tack.

To stick my neck out a bit, I hope this new tack gains some traction, because Mr Romney—whether you are a supporter of his or not—has indeed done his level best to avoid any serious discussion of his plans if elected, beyond arithmetically implausible promises to fix the deficit while cutting tax rates across the board and tidying up various tax breaks in a way that is both revenue neutral and distributionally neutral (ie, does not make the tax system more or less regressive), while refusing to spell out how this might work.

And I would like to think that such blatant obfuscation brings electoral penalties.

A lot of comments on this blog after this week's second presidential debate declare, with some force, that Mr Romney lost hands down to Mr Obama, because—to simplify—he was caught lying about his policy positions and his record and the president called him on those lies. Call it the fact-check argument. Now, the reporter in me has a lot of time for fact-checking, and for efforts to make politicians pay a price when they distort their record or their opponent's. But the commentator in me notes that Mr Romney is doing pretty well in the opinion polls at the moment, and does not seem to have had his momentum greatly slowed by the second debate. The neutral observer in me would also note that Mr Obama is not averse to giving the facts what older Fleet Street colleagues used to refer to as "a bit of vroom-vroom". And I stand by my observation that Mr Romney, while taking some heavy blows, also thumped Mr Obama with clear and effective language for a record of broken promises. At the end of the second debate, it seemed to me that Mr Obama had clearly pulled himself back into the race, after his disastrous first debate performance, but had not scored a knockout of Mr Romney. We were and are back where we were weeks ago: this is a neck and neck contest between a shifty challenger and a disappointing incumbent. But Mr Romney was lying, supporters of Mr Obama retort. Well here's the thing. Calling Mr Romney a liar is more or less a political dead end. The problem is that any political argument that degenerates into a "he said, he said" dispute instantly loses its ability to change minds or persuade the undecided. Accusations of lying are catnip to partisans, but to swing voters they are mostly noise, and off-putting noise.

But I have a hunch, just a hunch, that accusing Mitt Romney of serially hiding what he is up to might be more effective as a political tactic. The best political arguments reinforce a perception that voters already have about a candidate. And moderately attentive voters will recall that a severely conservative chap called Mitt Romney said all kinds of ferocious things about immigration, abortion and so on during the Republican primaries, and is now sounding like a Massachusetts centrist.

And minimally attentive voters in swing states will remember a barrage of Obama campaign attack ads on their televisions over the summer, accusing Mr Romney of hiding his money in foreign bank accounts (these ads worked, I can report: Mr Romney's Swiss bank accounts come up again and again when interviewing voters in swing states). And voters only just tuning in now will notice, for instance in the most recent debate, that Mr Romney dodges direct questions about which tax breaks he would abolish to make his sums add up, even when invited to say whether named items such as mortgage-interest relief, education credits or tax offsets for charitable donations are on the table.

Put that all together, with a dash of humour, and the Obama camp may have found an interesting line of attack. I noted, in my review of the second debate, that Mr Obama's best moment came when he said this:

Governor Romney was a very successful investor. If somebody came to you, governor, with a plan that said, "Here, I want to spend $7 or $8 trillion and we’re going to pay for it but we can’t tell you until maybe after the election how we’re going to do it." You wouldn’t have taken such a sketchy deal and neither would you, the American people.

The Obama camp clearly thinks it was a fine moment, because the president and allies are giving that "sketchy deal" line a lot of use (it helps that it triggers memories of the "Etch A Sketch" controversy of March, when Mr Romney's aide Eric Fehrnstrom told CNN that, after the Republican primary ended and the general-election campaign began: “It’s almost like an Etch A Sketch. You can kind of shake it up and restart all over again.”)

Bill Clinton, campaigning for Mr Obama in Ohio today, sought to wrap it together with Mr Romney's refusal to release more than two years of personal tax returns and the Romney campaign's current inability to say whether their nominee does or does not support the Lilly Ledbetter Act, a piece of law designed to help women bring lawsuits if they discover that they were paid less than men for the same work. As Mr Clinton put it:

This guy ran Bain Capital and is a business guy, and he’s hiding his budget? That ought to tell you something. He - well, he’s hiding his taxes, too, but he’s hiding his taxes in the years when he earned ordinary income. He’s given us two years when he was just running for president. And, he’s hiding whether he would have signed the Lilly Ledbetter act. He’s hiding everything. He doesn’t want you to think about him. He wants you to think, oh this economy is terrible. “I’m a jobs guy.” And as President Obama said in the debate, if I brought you a deal to Bain Capital and I said, fund my new business, I’ll give you the budget sometime in the future, just trust me on that - you wouldn’t give me one red cent, and we should not give him one vote on that.

My print column this week looks at Mr Romney's studied vagueness, and its specific implications for his running-mate, Paul Ryan. Mr Ryan, I argue, is revered by many conservatives as a teller of painful truths and a master of crunchy detail, who has the Midwestern down-home charm to make the case for austerity in a way that resonates with voters way outside the Republican base. Those same conservatives almost invariably add that Mr Ryan is a seven-term congressman from a majority Democrat district, proving that he has developed the language and the arguments to sell smaller government to voters way outside the Republican base.

Yet as Mr Romney's running-mate, the young fiscal hawk has not been telling painful truths about the budget. When it comes to eliminating tax breaks, he talks a lot about the need for leaders to put specific plans on the table, then fails to get specific. Asked about his radical plans for Medicare, he suggests that they are not radical at all.

(I can also report that it is a bit of a myth that Mr Ryan' district is a Democratic bastion. It went narrowly for Mr Obama in 2008, but went for Mr Bush in 2004 by an eight-point margin. It has been redistricted more than once since he first won it, removing some strongly Democratic towns in the south of the seat, and adding some heavily Republican rural bits in its north. A fair number of union members have also moved out of the district after two big car plants closed down. As a result, it is now mildly but distinctly Republican.)

After watching Mr Ryan campaign in Iowa, Michigan and Wisconsin, I can report that his Republican admirers do not care. Politicians say what they have to say to get elected, a long-time fan and neighbour of Mr Ryan's told me in Waukesha, Wisconsin. We trust his instincts.

That may work for established fans. But where does it leave Mr Ryan's pitch to be the truth-telling policy wonk with the common touch, who can reach out beyond the base? At best, I suggest, his pitch has not been tested by his run for vice-president.

Here is a link to the column.

(Photo credit: AFP)