The senior adviser to President Obama’s campaign is the latest part of the president’s team to emphasize early voting, something Team Obama sees as a winning strategy to ensure their supporters are voting in what is expected to be a very close election.

Obama cast his vote in Chicago on Thursday afternoon shortly after 4 p.m. Central time, also at the Martin Luther King Community Center.

“I'm told I'll be the first sitting president to take advantage of early voting,” the president wrote in an email to supporters earlier in the day.

The first lady voted by mail earlier in the month, a fact she has included in her stump speech ever since.

“Look, I voted early last week by mail,” she told a college crowd in Florida on Monday. “And if you were curious, I voted for Barack Obama. Yes, I did. There was no hesitation. I read his record, I took an objective look, and I said, this is the only one who can move this country forward: Barack Obama.”

Vice President Biden has also been talking about early voting, claiming last Friday in Florida, “We're winning the early voting."

GOP candidate Mitt Romney’s campaign disputes Biden’s claim. The two campaigns have been arguing over who has the edge on early voting ever since advance voting began in many states early this month.