Kirk, 53, had a stroke 10 months ago. Since January, he has under gone multiple brain surgeries and rigorous physical therapy. On Thursday, his staff announced he plans to be there for when the 113th Congress convenes.
"The timing is great for him to come back because the country could use his pragmatism," State Senator Matt Murphy, Palatine, said.
Illinois has been represented in Washington by just one senator, Democrat Dick Durbin, for the last year. Political experts say having the president from Chicago probably makes up for that, but Senator Kirk is a Republican who brings a unique military and foreign affairs background to Washington.
"It's better to have your representatives there, different opinions, they can work together," political scientist Paul Green said.
Senator Kirk told ABC7's Paul Meincke last month he plans to return to Washington with a legislative agenda that includes banning sewage dumping in the Great Lakes. Political observers say they expect him to be effective in Washington and in Illinois, in part because he's been straightforward with the voters during his recovery.
"I think the most important thing when Mark Kirk decides he's better is that he handled it with professionalism. And he was honest with the people."