Kirk prides himself on being a moderate, and the well wishes are coming from Republicans and Democrats. It's early in his recovery, but many colleagues expect him to return even as doctors predict it may be months before he can return to the active life of a senator.
Friends say Mark Kirk is a fighter -- politically and personally -- traits they hope will help him recover and resume his work in the Senate.
"His brain is going to function," said state Sen. Matt Murphy. "He'll be able to speak and all of the thins that made him a great Senator are going to come back and he'll be back."
Murphy's district overlapped with Kirk's old congressional district. The two campaigned together often. And those campaigns, friends say, showed his resilience.
When Kirk first ran to replace his boss, North Shore Congressman John Porter, in 2000 the election was a squeaker. His margin of victory was 2 percent.
"We knocked on a lot of doors together. I saw it personally. He exercised, is in good health. He did all the right things, and I think it was real important to him surviving this serious stroke," said Murphy.
Eight years after Kirk first went to Congress, another political close call: Once again, just two percentage points propelled Kirk to the Senate over Alexi Giannoulias.
Democratic Governor Pat Quinn released a statement saying: "We can all take comfort knowing that as a Navy commander, Sen. Kirk knows how to fight and he will fight through this to return to work."
On Friday, Kirk attended a going away party for a staffer. And those who were there say he showed no symptoms of the stroke that was to come.
"Everything seemed to be fine. Then apparently the next day, Saturday, he just wasn't feeling well and decided I have to get this checked out. He's always been real diligent about his health," said Murphy.
News of Kirk's stroke, the removal of part of his skull and a long rehabilitation process brought to mind the struggle of Rep. Gabrielle Giffords, of Arizona, who announced Sunday she would step down from Congress. While the traumas are very different, there are some parallels in the recovery, namely re-learning to use arms and legs.
The stroke did not affect the part of Kirk's brain that controls higher brain functions like talking.