If you showed at the duck hunt in Carhartt, you'd fit in -- in Washington D.C. not so much.

Suits are the uniform of the day there.

If you are concerned about roadblocks or attracting negative attention on the way in, considering traveling wearing a business suit.

If you are young you are a staffer. It doesn't have to be an expensive suit. You might even get away with a jacket, shirt, tie and khaki-type pants that don't match.

If you are older, you can still be a staffer (cheaper suit), or a lobbyist (expensive suit)

If you don't have a business haircut, you are an IT or other high-skill consultant that doesn't have to fully comply with norms.

If you have a military haircut and demeanor, you're consulting the Pentagon or are private security of some kind.

If there are 4 of you in a car, you are a consulting team. The older person is the team leader and is probably not driving.

White or Light Blue shirt. Tie probably should not be a color that screams politics.

Fit one of the models above, and chances are, if you get a look over, they'll think nothing of it and move on to someone who looks more "interesting".

Suits can suck if you are not used to them, but they invoke that Jedi Mind Trick: "These aren't the droids you are looking for."

Once on site, you can change out of the suit, or if you planned a personal visit to your Congresscritters to say thanks or something more pointed, that part of your visit should go easier.