You have a representative in the US Congress. That representative will be up for election in Nov 2010. If you would back that official in the next election, contact the district office and offer your services as a volunteer. If you are not happy with your current representative, you need to find someone who will be running against that person next year.
You can also contact your local Democratic or Republican Committee and offer to work for any candidates representing that party. You may have a US senate race in 2010, governor's race, etc. Those elected officials represent the people in your city so there is a need to reach out to voters in your area.