LOS ANGELES (MCT) — With his latest string of primary wins, Mitt Romney took another big step in his seemingly unstoppable march to the Republican presidential nomination. But his victories — and the way Romney achieved them — have taken a toll that could do lasting harm as he turns to the general election campaign against President Barack Obama.

In state after state, Romney has grown less popular the longer the campaign wears on and the better voters get to know him. The same thing happened in 2008, the first time Romney sought the GOP nomination.