What earthly power can make Mitt Romney release his tax returns? None whatsoever. Incredible as it may seem, it’s true: He can go all the way to November 6 without giving an inch, and there’s not one thing anyone can do about it. He pretty obviously thinks that the heat he’s taking for sitting on the returns is more bearable than the heat he’d have to endure by releasing them. And that calculation says something astonishing about the man, and ultimately, that is the issue here—this is far more about Romney’s character than it is about the money per se. And character is very quickly becoming the issue that the Obama camp hadn’t even planned on exploiting but now must, because Romney’s lack of it has become so obvious.

Yes, I think Harry Reid is hitting a little below the belt, as I wrote last week. But the bottom line here isn’t Reid. It’s the returns. Romney can, in one day, turn Harry Reid into a liar and a laughing stock. So why hasn’t he? There are just two possible explanations.

The first is that—and liberals and Democrats must bear this in mind—Romney might do just that. That is, maybe the information in the returns is embarrassing but no more than that, and Romney is just stringing everyone along. Say they reveal that Romney paid 11 percent or 9 percent or even 7 percent some years. That’s bad for him politically, but it’s not a nuclear bomb. And indeed, given how dark the speculation is right now about how whatever is in there must be terrible, this would be a pretty brilliant strategy: Let everything build to a fever pitch, with melodramatic speculation, and then, if the released returns reveal anything less serious than Reid’s charge (no taxes for a number of years), the media will decide that the Democrats overhyped the story.

OK. It’s a possibility. But it isn’t likely. Nothing about the way Romney comports himself suggests the above. That little chuckle of his is always the giveaway that he’s nervous. It’s the chuckle that came out involuntarily when ABC’s David Muir interviewed him on the subject in Israel, and it brings us to the other and more likely possibility—that something is very wrong indeed in the returns. So wrong, in fact, that he’d rather go through 13 more weeks of this than budge an inch.

Think about it. Through a week of a Democratic convention, when his tax returns will be mentioned by speaker after speaker. Through the early fall campaigning. Through the debates, when he will again say that he feels he’s revealed all he needs to reveal. Through the campaign’s final, home-stretch weeks. If he hasn’t released more returns, then by mid-October, this will be one of three main things the average American knows about Mitt Romney: that he’s rich, that he’s running for president, and that he won’t release his tax returns.

That will have to be devastating. And it will be something he brought completely on himself, either by refusing to release the returns or by doing whatever it is he did in the first place that he’s now hiding. My Beast colleague Peter Beinart is correct to write that how much Romney paid in taxes doesn’t have anything to do with the larger debate we’re having in this election about “whether the federal government should try to significantly regulate capitalism.” But it has everything to do with Romney’s character—his sense of entitlement, the Master-of-the-Universe-y aura of impatient superiority that was undoubtedly a great virtue in the corporate world but is very much the opposite in the civic one, and the weird insecurity that lurks underneath that veneer of über-confidence. And those things are very germane to what sort of president he’d be.

Hiding his tax returns is bad enough. But also hidden are the names of his bundlers, certain Salt Lake Olympic records, and records from his tenure as governor. That’s roughly ... oh, his entire career. It’s bad enough that he thinks he can make it to the White House in this fashion. But it’s worse that he wants to. Someone running for the presidency should be happy to share that information, especially when it’s your own father who blazed this particular trail in the first place.

The Obama campaign doesn’t seem to have planned on making character an issue. The Bain attacks were about qualifications, not character. But in these past three or four weeks, Romney has demonstrated, with America watching, that this is the issue with him. He doesn’t play it straight on anything. Voters can smell it on him like bad cologne, and the longer he digs in his heels on taxes, the greater the stink will grow.