Ex-Sen. tells crowd “I’m ready to lead” in official ’12 announcement Monday in Western PA.

Highlights from Santorum’s remarks:

Obama was given an economic problem, “but he kept digging.”

“He’s devalued our currency” and “he’s devalued our culture.”

America needs an “optimistic” leader who can meet nation’s challenges “not with big government, but with free people.”

Obama has “robbed people” of freedom. “Americans are not looking for someone they can believe in, they’re looking for a president who believes in them.”