I’ve watched with some bemusement this saga over Mitt Romney’s tax returns, which is now threatening to define the entire 2012 campaign. Romney has been running for President since 2006. Any remote sense of intelligence would have signaled to put the financial house in order at that time and lighten up on any aggressive tax avoidance, however legal. So six years of returns should be relatively painless. And yet, Romney continues to stonewall any requests for release of the documents:

“Oh, I think people in my party just say, ‘Look, this is a non-issue, just release the returns and it will all go away.’ My experience is that the Democratic Party these days has approached taxes in a very different way than in the past,” Romney told WPXI, an NBC Affiliate in Pittsburgh. “Their opposition people look for anything they can find to distort, to twist, and to try and make negative, and I want to make this a campaign about the economy and creating jobs. And they want to make this campaign about attacking people and diverting attention from our job picture in this country.”

The campaign’s already about attacking people, on both sides. There’s a conversation to be had on jobs, the economy, the role of Big Finance, the burning of the planet, the best way to deliver health care coverage to all Americans, how to keep seniors secure in retirement, and on and on. Nobody’s going to have that conversation. This is a campaign in 140 characters, the more biting the better. All the reticence on taxes does is inflate that particular issue so that it drowns out everything else, but if it died down some other issue would drown out everything else. It’s not like we’re capable in this country, with this media, of having an issues-based campaign.

So now Romney will have to endure more calls from his allies to release the tax returns. In the past 24 hours, Rick Perry and the National Review have come out in favor of that action. It will get worse with each passing today.

Which leads to speculation over just what’s so horrible in those tax returns that the Romney campaign is completely willing to hold out. The above Obama campaign ad does the speculation for him. With Romney releasing the 2010 and 2011 forms and holding back there, one working assumption is that 2008 and 2009, when stock prices fell rapidly, would have seen him book major losses, which potentially means that he paid no tax in those years, or had a negative tax rate. That’s definitely plausible. I think the idea that Romney took the 2009 Swiss bank account amnesty is a good one:

Romney might well have thought in 2007 and 2008 that there was nothing to fear about a non-disclosed offshore account he’d set up years earlier precisely because it wasn’t disclosed. But then came the settlement and the rush of non-disclosers to apply for the amnesty. Failing to apply for the amnesty and then getting charged by the IRS would have been both financially and politically disastrous. So amnesty it was. But even though the amnesty would eliminate any legal or financial liability for past acts, it would hardly eliminate political liability.

This is plausible precisely because either alternative would have forced disclosure on the tax form, so something either politically bad or criminally bad may sit on that 2009 form.

Either that, or he checked the “Yes I killed a hobo” box in 2006. You don’t want that getting out.