Sen. Mark Kirk

Mark Kirk

Mark Kirk at the Capitol in Washington, D.C., in January 2013. | U.S. Senate photo

Sen. Mark Kirk sits for interviews on Tuesday, January 2, 2013, the day before he returns to the U.S. Senate for the first time since suffering a stroke in January 2012. | U.S. Senate Photo Studio

After suffering a stroke a year ago, U.S. Senator Mark Kirk is back in Washington in this sit-down interview with the Chicago Sun-Times in the U.S. Capitol, one day before he will climb the Capitol steps after suffering his stroke. | U.S. Senate Photo Studio.

Senator Mark Kirk, after finishing Skyrise Chicago, the world's tallest stair climb at the Willis Tower. Sunday, November 4, 2012. I Brian Jackson~Sun-Times

U.S. Senators Dick Durbin (left) and Mark Kirk in May 2011. | Sun-Times Library

After suffering a stroke a year ago, U.S. Senator Mark Kirk is back in Washington in this sit-down interview with the Chicago Sun-Times in the U.S. Capitol, one day before he will climb the Capitol steps after suffering his stroke. | U.S. Senate Photo Studio.

U.S. Senator Mark Kirk during a sit-down interview with the Chicago Sun-Times in the U.S. Capitol in January 2013, one day before he climbed the Capitol steps after suffering his stroke. | U.S. Senate Photo Studio

After suffering a stroke a year ago, U.S. Senator Mark Kirk is back in Washington in this sit-down interview with the Chicago Sun-Times in the U.S. Capitol, one day before he will climb the Capitol steps after suffering his stroke. | U.S. Senate Photo Studio.

U.S. Sen. Mark Kirk sits down for an interview with the Chicago Sun-Times in January 2013 at the U.S. Capitol, one day before he climbed the Capitol steps, after suffering a stroke a year before. | U.S. Senate Photo Studio

After suffering a stroke a year ago, U.S. Senator Mark Kirk is back in Washington in this sit-down interview with the Chicago Sun-Times in the U.S. Capitol, one day before he will climb the Capitol steps after suffering his stroke. | U.S. Senate Photo Studio