"Lay off my wife."

So says Barack Obama about his controversial spouse, Michelle.

The Democratic candidate for the presidential nomination tends to dismiss any inconvenient fact as a "distraction" and to label every stinging criticism as "divisive." So even if he didn't have a husband's natural desire to defend his wife, he'd still probably denounce criticism of Michelle as beyond the pale.

Obama's comments came in the wake of a Tennessee GOP ad calling new attention to Michelle Obama's remark in February that she'd never been "really proud" of America until the nation embraced her husband's campaign.

"If they think that they're going to try to make Michelle an issue in this campaign, they should be careful," Obama said last week, "because that I find unacceptable, the notion that you start attacking my wife or my family."

Again, the Illinois senator's desire to protect his wife from criticism shows his heart's in the right place. The question is, where is his head?

If he truly finds it "unacceptable" for people to criticize his wife, he might want to rethink sending her out as his chief campaign surrogate, particularly when she has proved to be such a rich source of copy for journalists and barbs for critics.

And just out of curiosity, what does it mean, exactly, when a candidate finds something "unacceptable"? In a democracy, finding criticism unacceptable is a surefire way to drive yourself bonkers. It's like saying you find it unacceptable that bears use the woods for a bathroom. It's going to happen whether you accept it or not.

But the larger issue is whether Mrs. Obama - or any political spouse - is a legitimate subject for scrutiny and, yes, criticism. Historically, this hasn't been much of a problem because most politicians' wives played it safe. Sure, the crusading Eleanor Roosevelt had her bons mots, and Nancy Reagan had her moments in the spotlight, but most first ladies have stuck to ribbon cuttings, scone recipes and Girl Scout jamborees.

That all changed with Hillary Rodham Clinton. In 1992, she and her husband (now her ex-officio campaign manager) insisted that she wasn't the Tammy Wynette type. When her work as a lawyer came up during his campaign, she snapped, "I suppose I could have stayed home and baked cookies and had teas."

Bill Clinton, who himself said that electing him would deliver "two for the price of one," put her in charge of his top domestic priority, health-care reform. And though she failed miserably, she certainly wasn't sitting around baking cookies.

After that debacle, Hillary retreated into a more traditional first lady role for a while. Or so we thought. Now we're told that she was really a dynamo behind the scenes. Like that old "Saturday Night Live" skit in which Ronald Reagan was an amiable dunce in front of the cameras but a Patton-like commander in chief behind closed doors, the revisionist history of Hillary Clinton is that she was involved in everything, including dropping into the Balkans under sniper fire to conduct cowboy diplomacy. Or something like that.

It's worth recalling that during the 1992 campaign, Bill Clinton also tried to make any criticism of his wife unacceptable. When rival candidate Jerry Brown accused Bill of funneling money to Hillary's Arkansas law practice, Bill snapped: "You ought to be ashamed of yourself for jumping on my wife. You're not worth being on the same platform as my wife."

If Brown had accused Clinton of funneling money to someone else, say Hillary's colleague Webster Lee Hubbell, the vein-popping outrage wouldn't have worked. There's just something about wives that make husbands go all gallant. Trust me, I know.

But gallantry has to take a backseat when your wife is riding shotgun. Indeed, there might even be something sexist in all of this, somewhere. After all, no one thinks that criticizing Hillary's husband is "unacceptable."

Americans don't know Barack Obama very well. Part of the election process is getting to know the candidates. All politicians are desperate to control that process, but the rest of us aren't on their campaign staff and are under no obligation to follow orders.

Michelle Obama says some fascinating, substantive things. She appears to have a gloomy opinion of America, for instance, a country apparently full of desperate, isolated people whose only hope lies in an Obama presidency.

I, for one, want to hear more from her, and she seems perfectly willing to oblige. But if I don't like what she has to say, I reserve the right to say so, whether her husband finds it acceptable or not.