There's an old joke in the Texas pest-control community that the industry is basically obsolete because Texas bugs only come in two sizes: small enough to fit through the screen and big enough to open the door.
Thanks to our idiotic campaign finance laws, that's kind of how presidential campaigns can be classified these days, especially for members of Congress considering an early endorsement.
There is almost never much benefit for individual members of Congress -- especially backbenchers -- to endorse early on in the nomination process, whether you're talking about the candidates who are small enough to fit through the screens or the ones big enough to open the door.
To explain: The first type of presidential candidate is the insurgent outsider who lacks money, name identification and media attention.
These guys love getting endorsements, but they're extreme long shots. These are the single-issue candidates, the guys fighting for fourth-place finishes in Iowa to keep their campaign electricity bills paid.
They're good men, more often than not, but because of our campaign finance laws, they simply can't compete. These campaigns would love a congressman's endorsement, but how would it benefit the congressman politically to be associated with an almost certain loser?
These campaigns have little impact on the election, and the candidates atop them either go back to their day jobs or disappear from the public eye, with little or no currency to pay back their supporters -- that is, they're small enough to fit through the screen.
The other kinds of candidates are big enough to open the door. That is, you can endorse them as early as you want, but they won't care, because everyone else is busy endorsing them, too.
They know you're signing up mostly out of your own self-interest, so they have no reason to be all that grateful. What difference will it make to a possible President Hillary Clinton, in January of 2009, that some backbencher from Connecticut or Oregon endorsed her campaign in 2006?
After all, she was the Democratic front-runner for the 2008 presidential election at least as early as 1999. Sen. Clinton doesn't need endorsements; she's big enough to open the door for herself.
Being an underdog means never having to say you're sorry; being a prohibitive favorite means never having to say thank you.
So most members of Congress are faced with a Catch-22. Endorse a long shot, and no one will know; endorse a front-runner, and no one will care.
There are two factors that can lead to exceptions of this general rule. First is the ideological factor. If a young congressman wants to make a name for himself as an ideological standard-bearer, he might gain some street cred with the base by endorsing the most ideologically pure candidate, irrespective of his electability.
That might work for some members.
The other exception to endorsements' general meaninglessness is the revenge factor. This year's Democrat race provides a good example (as might the GOP races in 1988 and 2000, but less so).
Say you're a mainstream liberal Democrat congressman, an ambitious cog in the party's wheel. Right now you're basically facing a choice between Hillary Clinton and Barack Obama. If you endorse Sen. Clinton and then Sen. Obama wins, well, you can plead establishmentarianism.
"Everyone was endorsing Hillary," you could say, and it'd be mostly true. The party apparatus is lining up behind her, providing safety in numbers.
If Obama wins, he's going to need that giant apparatus to govern, and thus will have little choice but to forgive most of the Clintonistas. Hillary's endorsers thus have what amounts to a "Get Out of Jail Free" card they can hand to President Obama.
But what is good for the gander will not be what is good for the goose, and Democrats know it. If they endorse Obama, as I reckon most Democrats would if they had their druthers, and then Mrs. Clinton wins … well, in that case you might gain yourself a new job, perhaps Assistant Dog Catcher in the Yukon.
Indeed, if Sen. Obama shoots at the queen and misses, a lot of his supporters are going to realize that in the Democrat Party there's actually a third kind of bug: squashed.