Honestly, I would consider it a complete waste of money. Even if you donate a $1000 to politicians, especially ones on the national stage, this is just chump change to them. If you are in debt, this money would be much better served by going to pay for your own personal debts. If you were debt free living in a house (with the mortgage completely paid off) it would probably make at least a little sense but even then I personally won't do it.
Please keep in mind that a congressman or senator typically has 1000s or even 100,000 or 1,000,000 or more constituents. If you send them letters or give them money it just goes into a giant box with the 1000s of other letters people sent to them. You would be lucky to even get a staff member or intern to even notice your contribution.
So sorry to be negative about this. In grade school and some movies, we get a naive sense about the political process, in reality congressmen or congresswomen on both sides of the aisle are probably thinking more about how their votes affect their corporate donation contributors more than what you are sending them.
This is not to say that you can't make a difference. Often your own actions and money will much more greatly improve your life that relying on someone from the government to do it for you. If you want to clean up your town, you will get more done, by simply taking a broom and start sweeping the street or picking up garbage in front of your house that you would by sending money to a congressman.