MENTOR, Ohio — President Obama entered the final weekend of a bitter campaign on Saturday, a battle-scarred incumbent trying to recapture the mantle of ‘‘change’’ and the lofty ideals that propelled his lightning-in-a-bottle bid for the White House four years ago.

As he set off on a morning-to-midnight march through Ohio, Wisconsin, Iowa, and Virginia, Obama scoffed at Mitt Romney’s recent attempt to appropriate the change label, saying he was merely dressing up the failed policies of the George W. Bush administration.