Military Protocol?

I think military protocol would dictate using the official title. In this case, it would be "Senator". I sent a call out to three of my military friends who are officers to see what they think. Here are replies that I received:

"Either is appropriate depending upon the use."
"'Senator' and Last Name".

FYI: These are two of the most conservative friends I have. I almost second guessed them.

Even though I do not always agree with field negro,I do follow his blog.