That's just it. It is in opposition if it's a fact. The OP said President Obama is expanding government power. If it's a fact that government power is limited by the Constitution and Separation of Powers then no president can expand government power without circumventing these checks and balances. They may expand government influence but not government power. So for the OP to be correct I guess the claim is that President Obama is circumventing the Constitution, Congress and the Supreme Court?

Edit: Actually, I take that back. Since the citizenry and Congress can neglect their oversight duty, presidents can in fact increase government power, as evidenced recently by George Bush Jr. However, in theory the mechanisms exist to place limits on what any single person/politician can do. Making a blanket statement that Obama is increasing government power without providing specific arguments how is not substantive. After all, the same could be said by picking any of the other 43 presidents at random.