How music rights are handled in political ads and events

After reading The Song Machine last month, I'm not surprised at all that artists often don't have that much control over who uses their songs. Lately, this has brought some high-profile tension between music artists and political parties (mostly the RNC 2016/GOP). But if you're famous enough or if by chance you negotiated an amazing contract with your record label, I guess you have some say in how your songs get used. That's good news for musicians, right?