When Hillary Clinton wins the White House, she says Bill will be "a roaming ambassador to the world." What that means is rather unclear. We know he excels at roaming. Just ask Monica Lewinsky, Paula Jones, Kathleen Willey, etc.

But let's say he's conducting high level diplomatic consultations with Sultan bin Abdul Aziz Al Saud, Crown Prince of Saudi Arabia. Women do not have the right to vote in Saudi Arabia, so it is safe to say the Saudis don't have all that much confidence in a woman's political judgment. Let's say the Prince and Bill Clinton start reminiscing about the good ol' days when Bill was President, the treaties, the summits, the girls, the booze, whatever, and the Prince says that he liked Bill's Administration's policies concerning the Middle East better than those of his wife. He reminds Bill of the close personal friendship they developed over 8 years in the 1990's and says that while he appreciates that his wife is now President, that he, Bill, is the guy the Prince trusts. He reminds Bill that it is in the best interest of both countries that they have a harmonious relationship, and that he will not sign on to Hillary's new policy. He wants Bill's.

Hillary is quoted as saying "[Bill] has said he would do anything I asked him to do." Except, one presumes, not lying to her or cheating on her. What if, as a former President, with his own views on issues and, more importantly, his own legacy to consider, he decides to do what he wants? What happens then? Obviously if the Clintons had a remotely civilized marriage, they would talk it out. But we know about Hillary's dispute resolution methods, which involve thrown ashtrays and lamps. Which president will be running the country? Merely having to ask the question dilutes the power of the presidency and the country. We will waste precious energy and time reading tea leaves and statements from the White House and asking, which Clinton is responsible for this decision? We simply will not know.

Charles Krauthammer (from the right) and David Broder (from the left), have both raised this issue of the "two-headed presidency."

Krauthammer says:

It's deep unease about a shared presidency. Forget about Bill, the bad boy. The problem is William Jefferson Clinton, former president of the United States, commander in chief of the armed forces, George Washington's representative on Earth.

We have never had an ex-president move back into the White House. When in 1992 Bill Clinton promised "two for the price of one," it was taken as a slightly hyperbolic promotion of the role of first lady. This time we would literally be getting two presidents.

Any ex-president is a presence in his own right. His stature, unlike, say, Hillary's during Bill's presidency, is independent of his spouse. From Day One of Hillary's inauguration, Bill will have had more experience than she at everything she touches. His influence on her presidency would necessarily be immeasurably greater than that of any father on any son.

Americans did not like the idea of a co-presidency when, at the 1980 Republican convention, Ronald Reagan briefly considered sharing the office with former president Gerald Ford. (Ford would have been vice president with independent powers.) And they won't like this co-presidency, particularly because the Clinton partnership involves two characters caught in the dynamic of a strained, strange marriage.

The cloud hovering over a Hillary presidency is not Bill padding around the White House in robe and slippers flipping thongs. It's President Clinton, in suit and tie, simply present in the White House when any decision is made. The degree of his involvement in that decision will inevitably become an issue. Do Americans really want a historically unique two-headed presidency constantly buffeted by the dynamics of a highly dysfunctional marriage?

Broder, more gently, though in an article titled "The Icebergs Ahead For the Democrats,"

[T]his is a prospect that will test the tolerance of the American people far more severely than the possibility of the first female president -- or, for that matter, the first black president.

As my friend says, "there is nothing in American constitutional or political theory to account for the role of a former president, still energetic and active and full of ideas, occupying the White House with the current president."

No precedent exists for such an arrangement, and no ground rules have been -- or probably can be -- written. When Bill Clinton was president, the large policy enterprise that was entrusted to the first lady -- health-care reform -- crashed in ruins.

The causes were complex, and some of the burden falls on other people -- Republicans and Democrats in Congress, the interest groups and, yes, the press. But as one who reported and wrote in great detail and length about that whole enterprise, I can also tell you that the awkwardness of having an unelected but uniquely influential partner of the president in charge affected every step of the process, from the gestation of the plan to its final demise. She was never again asked to take on such a project.

And this was simply the confusion sown by having the first lady in charge. Put the former president into the picture -- however "sanitized" or insulated his role is supposed to be -- and the dimensions of the problem become even larger.

The spin will be about the "unique benefits" of the collective experience in a Hillary Clinton White House. "Collective experience" works well in any situation where "singular experience" would, by definition, be of lesser value. However, "collective experience" as applied to a White House with two spouses as presidents, is anything but better. It is a multiplier of problems that affects the very core of the power of the presidency.