In the days before the South Carolina primary, I struggled to figure out what was behind my mounting unease with Bill Clinton’s aggressive role in the campaign since New Hampshire. To give you some perspective, I don’t think there are many people who are bigger fans of Bill Clinton than I am or who’ve expended more ink defending him and his presidency. Nor am I particularly sold on Barack Obama’s candidacy.

Transcendence isn’t usually a big sell for me in politics. And I continue to have my doubts about whether Obama is tough enough or savvy enough to withstand the avalanche the Republicans will unleash against the Democratic nominee this fall. Nor have the attacks themselves been as vicious or as venomous as a lot of people in the media and Obama supporters have claimed.

So what’s the problem? What I’ve come up with is that seven years after he left the Oval Office, in many respects, Bill Clinton remains the leader of the Democratic Party. No, not in any formal way. But he remains extraordinarily popular among Democrats and he is almost unique in the last century as a successful Democratic president continuing to live on after his term of office.

He has come into a primary process between Hillary Clinton and Barack Obama and used his unique power to jam his thumb down on one side of the scale in a way that I think is very difficult for anyone to overcome. He holds what amounts to a de facto office within the Democratic Party. And what he’s been doing amounts to an abuse of office.

How is that fair? some will ask. Obama’s and Edwards’s spouses are vigorous advocates on their behalf; why can’t Bill do the same for Hillary? But this is silly. There’s no comparing Elizabeth Edwards or Michelle Obama to Bill Clinton.

Bill Clinton may owe all sorts of things to Hillary Clinton. I’m sure there’s a complicated mix of loyalty and love, the sense that he owes her, probably the sense that she’d be a great president. But back during impeachment folks like me made the point — and I think it was the right one — that Bill Clinton’s obligations to his wife, to his marriage, to sexual fidelity and so forth were an issue between him and his wife.

He had a different set of obligations and responsibilities to his supporters and to the larger public. And it was the latter that concerned me.

I think something similar applies in this case. I respect all the loyalties and devotions between the two of them in what is clearly a very complicated but also very enduring relationship. But I’m not part of that marriage. Its obligations aren’t any concern of mine and they have no claim on me.

My relationship with Bill Clinton is as a member of the party of which he is the leader — or at least the most revered elder statesman. And I feel like he’s been violating the compact that I have with him.

You might say that’s not fair, that that means his obligations as a husband and as a leader of his party are hopelessly in conflict. And I could only say you’re probably right. But that, frankly, is one of the reasons we have instinctive suspicions about dynastic politics.

And as I say, I can only see one side of the conflict. I’m not part of that marriage. And I can’t see putting the fate of the Democratic Party, or the country for that matter, into the balance of its obligations.

But there’s another layer to it. I think the Clinton campaign is only now realizing how much Bill’s aggressive advocacy has diminished Hillary. He has put her back under his shadow, where she hasn’t been for years.

For the moment, I doubt either of them is losing much sleep over that. Get through today and then worry about tomorrow.

But I think she looks much smaller now. Up until a couple days ago he was dominating the race. And that makes her look like a weaker figure — something that will not wear well in the general election.

It also suggests that this is going to be some sort of co-presidency. When Hillary’s getting knocked around by the folks on the Hill, is Bill going to go on Larry King to knock her enemies around? Will he be going off to foreign countries on his own little diplomatic missions?

I had assumed he’d remain a step in the background as he has through most of this decade. But that doesn’t seem to be the case. I was happy with Bill and I’d be happy with Hillary as president. But I don’t want them both.

The presidency is a singular job. It should stay that way. I hate seeing her being overshadowed by her spouse and having her husband bigfoot the process. It diminishes her and makes me think her presidency could be a four-year soap opera where Bill won’t shut up and let her have a shot at doing the job.

Marshall is editor of talkingpointsmemo.com .  His column appears in The Hill each week.  E-mail: This email address is being protected from spam bots, you need Javascript enabled to view it