Vice President Joe Biden, Sen. Joe Manchin, D-W. Va., and two Democratic colleagues from Illinois, Sen. Dick Durbin and Rep. Bobby Rush, joined Kirk as he climbed 45 steps, CNN reported. Other senators watched and cheered.
Kirk, 53, who had served five terms in the House, won the Illinois seat formerly held by President Barack Obama in November 2010. In January 2012 he suffered a devastating stroke that required him to learn to walk again.
Lance Trover, Kirk's communications director, said the senator will use a wheelchair in the Capitol's long hallways but can walk with a four-pronged cane, the Chicago Tribune reported. He is now living in a handicapped accessible apartment in Washington and made a surprise appearance at a holiday party for his staff just before Christmas.
Rep. John Shimkus, R-Ill., who first visited Kirk in an Illinois hospital in March, said he expects Kirk to be "slower-paced -- not the guy running down the hallways, not like Chatty Cathy anymore. He's going to be listening, and very deliberative."