Email is great, but it is too easy to filter. In this age of auto-response, you would never get the message to them. But, if a cart full of postcards were delivered each day, it would have two effects.
Firstly, the volume could become overwhelming. The cost of a postcard isn't that much, and if each interested party could enlist the assistance of a few others, a lot of cards could be sent. It currently costs $ .24 to send a postcard, so you could send a hundred for $24. It would be difficult to ignore the volume of paper.
It should be easy to get a couple hundred cards filled out, by going to the local watering holes, or shopping centers, and setting up a table. Put a jar on the table to solicit money for printing cartridges (buy card kits at WalMart to piss off a few more folks) and stamps, but plan on sending them out on your dime.
Secondly, it would irritate the hell out of all the "greenies", to think of all those poor trees... but the paper companies will love us!
I also think postcards are a good idea if you buy them yourself and have them ready to simply sign and send in.
White postcards with a matte finish can be purchased cheaply in a box of 200 at Office Depot (Item # 915-895) and probably Staples too. The work great with both inkjet and laserjet printers.
Suggest using that "Gringo Peso" image that one of the FReepers designed as the front of the card with a handwritten note to your congress critters on the back.