Obama also chided McCain for another new commercial that promises " change that we need . " " Sound familiar ? " said Obama , who has made " change " the central theme of his campaign . " Let me tell you , instead of borrowing my lines he needs to borrow some of my ideas . Change is n't about slogans . It 's about substance . " He also took a little poke at McCain 's running mate , Gov.

Answer the following question: Why would Obama be talking about McCain like that ?
They are political rivals .