Senator Mark Kirk, R-Ill., underwent "successful" surgery in Chicago this morning for a stroke, according to a statement released by his office.

"On Saturday, Senator Kirk checked himself into Lake Forest Hospital, where doctors discovered a carotid artery dissection in the right side of his neck," according to the statement. "He was transferred to Northwestern Memorial Hospital in Chicago, where further tests revealed that he had suffered an ischemic stroke.  Early this morning the Senator underwent surgery to relieve swelling around his brain stemming from the stroke. The surgery was successful."

Senator Kirk is young by Senate standards - just 52 years old. Kirk came into Congress when he won the seat formerly occupied by Senator Barack Obama.

Today is the Senate's first day back after nearly a three-week recess.  Kirk will miss today's first votes scheduled for late this afternoon.

"Due to his young age, good health and the nature of the stroke, doctors are very confident in the Senator's recovery over the weeks ahead," his office said in a statement today.

The Senator's doctors will hold a press conference at Northwestern Memorial Hospital today to provide an update on the Senator's condition.