President Barack Obama criticized Republicans as champions of the wealthy over the middle class Tuesday night as he told Democrats gathered for the Iowa caucuses that he is more optimistic now than he was four years ago.

"We've already seen change take place," Mr. Obama said, speaking from a Hilton hotel in Washington through a live video feed to Iowa supporters. He added that 2012 is partly about "reminding the American people how far we've traveled…but part of it is also framing this larger debate about what kind of country...