WASHINGTON -- Sen. John McCain (R-Ariz.) is standing by a recent Mitt Romney ad attacking President Barack Obama on the economy, even though it mirrors a spot the Obama campaign aired against McCain in 2008 that the senator criticized at the time.The 2008 Obama ad quoted McCain, at the time the GOP presidential nominee, saying, "The fundamentals of our economy are strong." At the end, it asked: "How can John McCain fix our economy if he doesn't understand it's broken?"The Romney ad quotes Obama saying "the private sector is doing fine." It ends with: "How can President Obama fix our economy if he doesn't understand it's broken?"Read More... More on Barack Obama 2012