A jacket like this, with bold brass buttons, can be a challenge. What do you wear with it? It's tempting to go very very simple, like plain white tee kind of simple. And you can. But the other direction is to run with the nautical theme to a point. In this case, the Congresswoman chose a narrow striped oxford shirt and rounded gold jewelry that coordinates with the buttons. This is one time where matching your earrings and necklace is a good thing - mixing it up would just leave you with too much going on. Even her official House pin goes with the nautical theme in a way.
As I said, this works as long as you only take it so far. What's too far? Earrings shaped like anchors, any kind of rope detail on the blouse, a red handkerchief. You get the idea.