The president is in campaign mode, even though it's not yet clear who his opponent will be.
Four days before the Illinois primary, Mitt Romney was attacking President Obama on his home turf Friday.
"He's out there pushing for alternative energy, we're pushing for an alternative to the president," Romney told supporters.
President Obama was in Chicago to answer back.
He declared he cares about values, too.
"Hard work is a value. Looking out for one another. The idea that we're all in this together - I'm my brother's keeper and sister's keep, that's a value," he said to loud applause.
Romney needs a strong showing in Illinois after losing to Rick Santorum in Alabama and Mississippi.
Santorum is clearly connecting with conservatives, so Romney's trying to change the conversation by focusing on the economy.
Romney and Santorum are also fighting for Puerto Rico, which holds its primary on Sunday, and language has become a hot-button issue.
Santorum's trip ended in controversy, with him denying he said Puerto Ricans need to adopt English if they want to become a state.
Santorum's campaign insists he was maliciously misquoted, but the story became the headline of his Puerto Rican trip.