President Obama made a televised speech to the nation regarding the Gulf Oil Spill. Immediately, the political opposition accused him of doing so for "political advantage". Well, Duuuh . . . Of course he did, he's a POLITICIAN. They always do things for political advantage by definition.
It's little different than other entities. Companies do things to maximize their profits, non-profit groups do things to further their interests, unions do things to increase their membership and gain advantage for their members. We all do things which benefit us when possible. The key with politicians, companies, groups is to make sure that the "national good" aligns with their "good".
If you can prove to a politician that something will help get them elected, they will jump on it. If you can prove to a company that something will benefit their bottom line, they will jump on it, and so on. Enlightened seif-interested is the key. The hard part is aligning that with the interests of the country/world as a whole.