As an active member of the U.S. electorate, you may want to contact your senator to express your opinion on pending legislation or share your viewpoint on a recent event. To address a senator, use official titles and a respectful tone....
www.google.com
Of the many Google search results, this was the easiest.
My opinion is you do not address the board as you are applying for the senators (representative) nomination. And they choose to use a board as part of their process.