Then there’s Mr. Romney’s frequent suggestion that the president has gone around the world “apologizing for America.” This is a popular theme on the right — but the so-called Obama apology tour is a complete fabrication, assembled by taking quotes out of context.

As Greg Sargent of The Washington Post has pointed out, there’s a common theme to these whoppers and a number of other things Mr. Romney has said: the strategy is clearly to portray the president as a suspect character, someone who doesn’t share American values. And since Mr. Obama has done and said nothing to justify this portrait, Mr. Romney just invents stuff to make his case.

But won’t there be some blowback? Won’t Mr. Romney pay a price for running a campaign based entirely on falsehoods? He obviously thinks not, and I’m afraid he may be right.

Oh, Mr. Romney will probably be called on some falsehoods. But, if past experience is any guide, most of the news media will feel as though their reporting must be “balanced,” which means that every time they point out that a Republican lied they have to match it with a comparable accusation against a Democrat — even if what the Democrat said was actually true or, at worst, a minor misstatement.

This isn’t an abstract speculation. Politifact, the project that is supposed to enforce truth in politics, has declared Democratic claims that Republicans voted to end Medicare its “Lie of the Year.” It did so even though Republicans did indeed vote to dismantle Medicare as we know it and replace it with a voucher scheme that would still be called “Medicare,” but would look nothing like the current program — and would no longer guarantee affordable care.

So here’s my forecast for next year: If Mr. Romney is in fact the Republican presidential nominee, he will make wildly false claims about Mr. Obama and, occasionally, get some flack for doing so. But news organizations will compensate by treating it as a comparable offense when, say, the president misstates the income share of the top 1 percent by a percentage point or two.

The end result will be no real penalty for running an utterly fraudulent campaign. As I said, welcome to post-truth politics.