This is difficult to write. My grandfather suffered through dementia for the last 15 years of his life. It’s never easy to talk about, and in politics, it’s particularly difficult because of all the potential for cheap-shot concern-trolling…

But there’s a dirty little secret everyone is keeping in Pennsylvania and Washington. It isn’t difficult to puzzle it out for yourself; in fact, given the circumstances, it’s probably difficult to avoid developing nagging suspicions. But there are a lot of stories being told off the record and in hushed whispers. Tonight, I’ve decided to stop whispering and come forward with my own.

First, background. You’ve probably heard the story about Senator Specter telling Michelle Bachmann to “act like a lady”. Before that, I interviewed him and when I tried to follow up with a related question, he looked at me and firmly told me he’d like to finish his sentence (about 1:30 – 2:15 in the video below). I demurred, and he told me to go ahead and ask my next question. It appears as if he had lost his train of thought…

That’s kinda weird, but nothing compared to what happened a few weeks later.

In the basement of the Russell Senate office building, there is a subway that ferries Senators and staff to and from the Capitol. Senator Spector was making his way over to the Capitol to cast a vote when I caught up with him and asked if he had decided to support or oppose the Bernanke nomination. He said he hadn’t decided. I asked him if he knew that Bernanke had said he was less concerned about unemployment than inflation. Specter answered gruffly that he was still making up his mind. Then he walked over to a call-button for the subway and pressed it several times.

The subway was already in the station.

It’s not like you can hide a subway.

The guard behind us yelled to the Senator, “Senator, he’s right there!” The driver of the subway yelled to the Senator, “Senator, I’m right here!” Specter continued to press the button for another coupla seconds before suddenly realizing the subway was already in the station and boarding.

Look… Does anyone think Specter makes the mistake he made with Bachmann 5 or 10 years ago? 5 or 10 years ago, does he awkwardly climb up on the stage while his primary opponent is being interviewed at an event ? At least Kanye West was drunk!

Dementia isn’t something you wake up with one morning. It’s not something that comes upon you suddenly… It’s a progressive affliction.

The problem for Specter and Pennsylvanian’s trying to decide who to support in the primary is that the decision is one they’ll be saddled with for six years (assuming Specter can beat Toomey). If Specter is showing signs of dementia today, they are pretty mild. He’s still capable of campaigning, legislating and, in general, doing what he needs to do to be relevant today. The problem is he can do all that with 95% of the capacity he had 5 years ago. But next year where will he be? 92%? 90%? 80%?

Or worse, for Democrats at least… will his 95% be good enough to beat Toomey? Will his loss of a mental step create the gaffe that makes him unelectable – after he wins the primary?

In the end, after seeing the Senator up close, as a progressive, I’m nervous. The Obama administration, Governor Rendell and DSCC will support Specter right up until primary day. Maybe that’s the price they paid to get Harry Reid his enormously consequential 60th vote. It’d suck quite a bit if an unanticipated cost of that deal turned out to be a newly-minted Senator Toomey.