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.
Tom DeLay is the former House Majority Leader, the second ranking leader in the United States House of Representatives, and co-author of No Retreat, No Surrender: One American's Fight.