During a surprise campaign stop at a field office in Chicago, President Obama congratulated Mitt Romney on a hard-fought campaign.

The president's congratulatory comment was not meant to be a premature concession. He said he's confident about the results. "I'm looking forward to the results. And I expect that we'll have a good night," he said.

Mr. Obama encouraged all voters to head to the polls: "I would encourage everybody on all sides just to make sure that you exercise this precious right that you have that people fought so hard for, for us to have."

The president's remarks came after he made several calls to campaign volunteers working until the last minute to reelect him.

"Hi is this Annie? This is Barack Obama," he said to the person on the other end of the line in Wisconsin."This is Barack Obama. You know, the president?"

"She was very nice to me even though she initially didn't know who I was," Mr. Obama said when the call ended.

He used a cell phone to make several calls to thank volunteers working in Wisconsin for their help. "With all the work you guys are doing I'm sure were going to win Wisconsin," he said to one caller.

Meantime,